Java DB Reference Manual
Version 10.5
Derby Document build:
August 10, 2009, 9:51:45 AM (EDT)




Version 10.5   Java DB Reference Manual
   
Contents
Copyright    
License    
Relationship between Java DB and Derby    
About this guide    
Purpose of this document    
Audience    
How this guide is organized    
SQL language reference    
Capitalization and special characters    
SQL identifiers    
Rules for SQL92 identifiers    
SQL92Identifier    
column-Name    
correlation-Name    
new-table-Name    
schemaName    
Simple-column-Name    
synonym-Name    
table-Name    
view-Name    
index-Name    
constraint-Name    
cursor-Name    
TriggerName    
AuthorizationIdentifier    
RoleName    
Statements    
Interaction with the dependency system    
ALTER TABLE statement    
CALL (PROCEDURE) statement    
CREATE statements    
DECLARE GLOBAL TEMPORARY TABLE statement    
DELETE statement    
DROP statements    
GRANT statement    
INSERT statement    
LOCK TABLE statement    
RENAME statements    
REVOKE statement    
SET statements    
SELECT statement    
UPDATE statement    
SQL clauses    
CONSTRAINT clause    
FOR UPDATE clause    
FROM clause    
GROUP BY clause    
HAVING clause    
ORDER BY clause    
The result offset and fetch first clauses    
WHERE clause    
WHERE CURRENT OF clause    
SQL expressions    
SelectExpression    
TableExpression    
VALUES expression    
Expression precedence    
Boolean expressions    
Dynamic parameters    
JOIN operations    
INNER JOIN operation    
LEFT OUTER JOIN operation    
RIGHT OUTER JOIN operation    
SQL queries    
Query    
ScalarSubquery    
TableSubquery    
Built-in functions    
Standard built-in functions    
Aggregates (set functions)    
ABS or ABSVAL function    
ACOS function    
ASIN function    
ATAN function    
ATAN2 function    
AVG function    
BIGINT function    
CASE expressions    
CAST function    
CEIL or CEILING function    
CHAR function    
Concatenation operator    
COS function    
COSH function    
COT function    
COUNT function    
COUNT(*) function    
CURRENT DATE function    
CURRENT_DATE function    
CURRENT ISOLATION function    
CURRENT_ROLE function    
CURRENT SCHEMA function    
CURRENT TIME function    
CURRENT_TIME function    
CURRENT TIMESTAMP function    
CURRENT_TIMESTAMP function    
CURRENT_USER function    
DATE function    
DAY function    
DEGREES function    
DOUBLE function    
EXP function    
FLOOR function    
HOUR function    
IDENTITY_VAL_LOCAL function    
INTEGER function    
LCASE or LOWER function    
LENGTH function    
LN or LOG function    
LOG10 function    
LOCATE function    
LTRIM function    
MAX function    
MIN function    
MINUTE function    
MOD function    
MONTH function    
NULLIF expressions    
PI function    
RADIANS function    
RANDOM function    
RAND function    
ROW_NUMBER function    
RTRIM function    
SECOND function    
SESSION_USER function    
SIGN function    
SIN function    
SINH function    
SMALLINT function    
SQRT function    
SUBSTR function    
SUM function    
TAN function    
TANH function    
TIME function    
TIMESTAMP function    
TRIM function    
UCASE or UPPER function    
USER function    
VARCHAR function    
XMLEXISTS operator    
XMLPARSE operator    
XMLQUERY operator    
XMLSERIALIZE operator    
YEAR function    
Built-in system functions    
SYSCS_UTIL.SYSCS_CHECK_TABLE system function    
SYSCS_UTIL.SYSCS_GET_DATABASE_PROPERTY system function    
SYSCS_UTIL.SYSCS_GET_RUNTIMESTATISTICS system function    
SYSCS_UTIL.SYSCS_GET_USER_ACCESS system function    
Built-in system procedures    
SYSCS_UTIL.SYSCS_BACKUP_DATABASE system procedure    
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_NOWAIT system procedure    
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE system procedure    
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE_NOWAIT system procedure    
SYSCS_UTIL.SYSCS_EMPTY_STATEMENT_CACHE system procedure    
SYSCS_UTIL.SYSCS_CHECKPOINT_DATABASE system procedure    
SYSCS_UTIL.SYSCS_COMPRESS_TABLE system procedure    
SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE system procedure    
SYSCS_UTIL.SYSCS_DISABLE_LOG_ARCHIVE_MODE system procedure    
SYSCS_UTIL.SYSCS_EXPORT_TABLE system procedure    
SYSCS_UTIL.SYSCS_EXPORT_TABLE_LOBS_TO_EXTFILE system procedure    
SYSCS_UTIL.SYSCS_EXPORT_QUERY system procedure    
SYSCS_UTIL.SYSCS_EXPORT_QUERY_LOBS_TO_EXTFILE system procedure    
SYSCS_UTIL.SYSCS_IMPORT_DATA system procedure    
SYSCS_UTIL.SYSCS_IMPORT_DATA_LOBS_FROM_EXTFILE system procedure    
SYSCS_UTIL.SYSCS_IMPORT_TABLE system procedure    
SYSCS_UTIL.SYSCS_IMPORT_TABLE_LOBS_FROM_EXTFILE system procedure    
SYSCS_UTIL.SYSCS_FREEZE_DATABASE system procedure    
SYSCS_UTIL.SYSCS_UNFREEZE_DATABASE system procedure    
SYSCS_UTIL.SYSCS_RELOAD_SECURITY_POLICY system procedure    
SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY system procedure    
SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS system procedure    
SYSCS_UTIL.SYSCS_SET_STATISTICS_TIMING system procedure    
SYSCS_UTIL.SYSCS_SET_USER_ACCESS system procedure    
SYSCS_UTIL.SYSCS_UPDATE_STATISTICS system procedure    
SYSCS_DIAG diagnostic tables and functions    
Data types    
Built-In type overview    
Numeric types    
Data type assignments and comparison, sorting, and ordering    
BIGINT data type    
BLOB data type    
CHAR data type    
CHAR FOR BIT DATA data type    
CLOB data type    
DATE data type    
DECIMAL data type    
DOUBLE data type    
DOUBLE PRECISION data type    
FLOAT data type    
INTEGER data type    
LONG VARCHAR data type    
LONG VARCHAR FOR BIT DATA data type    
NUMERIC data type    
REAL data type    
SMALLINT data type    
TIME data type    
TIMESTAMP data type    
VARCHAR data type    
VARCHAR FOR BIT DATA data type    
XML data type    
Argument matching    
SQL reserved words    
Derby support for SQL-92 features    
Derby system tables    
SYSALIASES system table    
SYSCHECKS system table    
SYSCOLPERMS system table    
SYSCOLUMNS system table    
SYSCONGLOMERATES system table    
SYSCONSTRAINTS system table    
SYSDEPENDS system table    
SYSFILES system table    
SYSFOREIGNKEYS system table    
SYSKEYS system table    
SYSROLES system table    
SYSROUTINEPERMS system table    
SYSSCHEMAS system table    
SYSSTATISTICS system table    
SYSSTATEMENTS system table    
SYSTABLEPERMS system table    
SYSTABLES system table    
SYSTRIGGERS system table    
SYSVIEWS system table    
Derby exception messages and SQL states    
SQL error messages and exceptions    
JDBC reference    
java.sql.Driver interface    
java.sql.Driver.getPropertyInfo method    
java.sql.DriverManager.getConnection method    
Derby database connection URL syntax    
Syntax of database connection URLs for applications with embedded databases    
Additional SQL syntax    
Attributes of the Derby database connection URL    
java.sql.Connection interface    
java.sql.Connection.setTransactionIsolation method    
java.sql.Connection.setReadOnly method    
java.sql.Connection.isReadOnly method    
Connection functionality not supported    
java.sql.DatabaseMetaData interface    
DatabaseMetaData result sets    
java.sql.DatabaseMetaData.getProcedureColumns method    
Parameters to getProcedureColumns    
Columns in the ResultSet returned by getProcedureColumns    
java.sql.DatabaseMetaData.getBestRowIdentifier method    
java.sql.Statement interface    
ResultSet objects    
Autogenerated keys    
java.sql.CallableStatement interface    
CallableStatements and OUT Parameters    
CallableStatements and INOUT Parameters    
java.sql.PreparedStatement interface    
Prepared statements and streaming columns    
java.sql.ResultSet interface    
ResultSets and streaming columns    
java.sql.ResultSetMetaData interface    
java.sql.SQLException class    
java.sql.SQLWarning class    
java.sql.Savepoint interface    
Mapping of java.sql.Types to SQL types    
Mapping of java.sql.Blob and java.sql.Clob interfaces    
JDBC Package for Connected Device Configuration/Foundation Profile (JSR 169)    
JDBC 4.0-only features    
Refined subclasses of SQLException    
java.sql.Connection interface: JDBC 4.0 features    
java.sql.DatabaseMetaData interface: JDBC 4.0 features    
java.sql.Statement interface: JDBC 4.0 features    
javax.sql.DataSource interface: JDBC 4.0 features    
java.sql.SQLXML interface    
JDBC escape syntax    
JDBC escape keyword for call statements    
JDBC escape syntax    
JDBC escape syntax for LIKE clauses    
JDBC escape syntax for fn keyword    
JDBC escape syntax for outer joins    
JDBC escape syntax for time formats    
JDBC escape syntax for date formats    
JDBC escape syntax for timestamp formats    
Setting attributes for the database connection URL    
bootPassword=key attribute    
collation=collation attribute    
create=true attribute    
createFrom=path attribute    
databaseName=nameofDatabase attribute    
dataEncryption=true attribute    
encryptionKey=key attribute    
encryptionProvider=providerName attribute    
encryptionAlgorithm=algorithm attribute    
failover=true attribute    
logDevice=logDirectoryPath attribute    
newEncryptionKey=key attribute    
newBootPassword=newPassword attribute    
password=userPassword attribute    
restoreFrom=path attribute    
rollForwardRecoveryFrom=path attribute    
securityMechanism=value attribute    
shutdown=true attribute    
slaveHost=hostname attribute    
slavePort=portValue attribute    
startMaster=true attribute    
startSlave=true attribute    
stopMaster=true attribute    
stopSlave=true attribute    
territory=ll_CC attribute    
traceDirectory=path attribute    
traceFile=path attribute    
traceFileAppend=true attribute    
traceLevel=value attribute    
upgrade=true attribute    
user=userName attribute    
ssl=sslMode attribute    
Creating a connection without specifying attributes    
Derby property reference    
Scope of Derby properties    
Dynamic and static properties    
Derby properties    
derby.authentication.ldap.searchAuthDN    
derby.authentication.ldap.searchAuthPW    
derby.authentication.ldap.searchBase    
derby.authentication.ldap.searchFilter    
derby.authentication.provider    
derby.authentication.server    
derby.connection.requireAuthentication    
derby.database.defaultConnectionMode    
derby.database.forceDatabaseLock    
derby.database.fullAccessUsers    
derby.database.noAutoBoot    
derby.database.propertiesOnly    
derby.database.readOnlyAccessUsers    
derby.database.sqlAuthorization    
derby.infolog.append    
derby.jdbc.xaTransactionTimeout    
derby.language.logQueryPlan    
derby.language.logStatementText    
derby.locks.deadlockTimeout    
derby.locks.deadlockTrace    
derby.locks.escalationThreshold    
derby.locks.monitor    
derby.locks.waitTimeout    
derby.replication.logBufferSize    
derby.replication.maxLogShippingInterval    
derby.replication.minLogShippingInterval    
derby.replication.verbose    
derby.storage.initialPages    
derby.storage.minimumRecordSize    
derby.storage.pageCacheSize    
derby.storage.pageReservedSpace    
derby.storage.pageSize    
derby.storage.rowLocking    
derby.storage.tempDirectory    
derby.stream.error.field    
derby.stream.error.file    
derby.stream.error.method    
derby.stream.error.logSeverityLevel    
derby.system.bootAll    
derby.system.durability    
derby.system.home    
derby.user.UserName    
J2EE Compliance: Java Transaction API and javax.sql Interfaces    
The JTA API    
Notes on Product Behavior    
javax.sql: JDBC Interfaces    
Derby API    
Stand-alone tools and utilities    
JDBC implementation classes    
JDBC driver    
Data Source Classes    
Miscellaneous utilities and interfaces    
Supported territories    
Derby limitations    
Limitations for database manager values    
DATE, TIME, and TIMESTAMP limitations    
Limitations on identifier length    
Numeric limitations    
String limitations    
XML limitations    
Trademarks    


Java DB Reference Manual
Apache Software FoundationJava DB Reference ManualApache Derby
Copyright
Copyright 2004-2009 The Apache Software Foundation
Copyright 2009 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, California 95054, U.S.A.
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.
Related information
License
The Apache License, Version 2.0
Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. "License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document. "Licensor" shall mean the copyright owner or entity authorized by the copyright owner that is granting the License. "Legal Entity" shall mean the union of the acting entity and all other entities that control, are controlled by, or are under common control with that entity. For the purposes of this definition, "control" means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity. "You" (or "Your") shall mean an individual or Legal Entity exercising permissions granted by this License. "Source" form shall mean the preferred form for making modifications, including but not limited to software source code, documentation source, and configuration files. "Object" form shall mean any form resulting from mechanical transformation or translation of a Source form, including but not limited to compiled object code, generated documentation, and conversions to other media types. "Work" shall mean the work of authorship, whether in Source or Object form, made available under the License, as indicated by a copyright notice that is included in or attached to the work (an example is provided in the Appendix below). "Derivative Works" shall mean any work, whether in Source or Object form, that is based on (or derived from) the Work and for which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship. For the purposes of this License, Derivative Works shall not include works that remain separable from, or merely link (or bind by name) to the interfaces of, the Work and Derivative Works thereof. "Contribution" shall mean any work of authorship, including the original version of the Work and any modifications or additions to that Work or Derivative Works thereof, that is intentionally submitted to Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner. For the purposes of this definition, "submitted" means any form of electronic, verbal, or written communication sent to the Licensor or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, the Licensor for the purpose of discussing and improving the Work, but excluding communication that is conspicuously marked or otherwise designated in writing by the copyright owner as "Not a Contribution." "Contributor" shall mean Licensor and any individual or Legal Entity on behalf of whom a Contribution has been received by Licensor and subsequently incorporated within the Work. 2. Grant of Copyright License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form. 3. Grant of Patent License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer the Work, where such license applies only to those patent claims licensable by such Contributor that are necessarily infringed by their Contribution(s) alone or by combination of their Contribution(s) with the Work to which such Contribution(s) was submitted. If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or a Contribution incorporated within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed. 4. Redistribution. You may reproduce and distribute copies of the Work or Derivative Works thereof in any medium, with or without modifications, and in Source or Object form, provided that You meet the following conditions: (a) You must give any other recipients of the Work or Derivative Works a copy of this License; and (b) You must cause any modified files to carry prominent notices stating that You changed the files; and (c) You must retain, in the Source form of any Derivative Works that You distribute, all copyright, patent, trademark, and attribution notices from the Source form of the Work, excluding those notices that do not pertain to any part of the Derivative Works; and (d) If the Work includes a "NOTICE" text file as part of its distribution, then any Derivative Works that You distribute must include a readable copy of the attribution notices contained within such NOTICE file, excluding those notices that do not pertain to any part of the Derivative Works, in at least one of the following places: within a NOTICE text file distributed as part of the Derivative Works; within the Source form or documentation, if provided along with the Derivative Works; or, within a display generated by the Derivative Works, if and wherever such third-party notices normally appear. The contents of the NOTICE file are for informational purposes only and do not modify the License. You may add Your own attribution notices within Derivative Works that You distribute, alongside or as an addendum to the NOTICE text from the Work, provided that such additional attribution notices cannot be construed as modifying the License. You may add Your own copyright statement to Your modifications and may provide additional or different license terms and conditions for use, reproduction, or distribution of Your modifications, or for any such Derivative Works as a whole, provided Your use, reproduction, and distribution of the Work otherwise complies with the conditions stated in this License. 5. Submission of Contributions. Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions. Notwithstanding the above, nothing herein shall supersede or modify the terms of any separate license agreement you may have executed with Licensor regarding such Contributions. 6. Trademarks. This License does not grant permission to use the trade names, trademarks, service marks, or product names of the Licensor, except as required for reasonable and customary use in describing the origin of the Work and reproducing the content of the NOTICE file. 7. Disclaimer of Warranty. Unless required by applicable law or agreed to in writing, Licensor provides the Work (and each Contributor provides its Contributions) on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of using or redistributing the Work and assume any risks associated with Your exercise of permissions under this License. 8. Limitation of Liability. In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall any Contributor be liable to You for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages. 9. Accepting Warranty or Additional Liability. While redistributing the Work or Derivative Works thereof, You may choose to offer, and charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations and/or rights consistent with this License. However, in accepting such obligations, You may act only on Your own behalf and on Your sole responsibility, not on behalf of any other Contributor, and only if You agree to indemnify, defend, and hold each Contributor harmless for any liability incurred by, or claims asserted against, such Contributor by reason of your accepting any such warranty or additional liability. END OF TERMS AND CONDITIONS APPENDIX: How to apply the Apache License to your work. To apply the Apache License to your work, attach the following boilerplate notice, with the fields enclosed by brackets "[]" replaced with your own identifying information. (Don't include the brackets!) The text should be enclosed in the appropriate comment syntax for the file format. We also recommend that a file or class name and description of purpose be included on the same "printed page" as the copyright notice for easier identification within third-party archives. Copyright [yyyy] [name of copyright owner] Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
Relationship between Java(TM) DB and Derby
Java(TM) DB is a relational database management system that is based on the Java programming language and SQL. Java DB is a commercial release of the Apache Software Foundation's (ASF) open source relational database project. The Apache project is called Derby.
The Java DB product includes Derby without any modification whatsoever to the underlying source code.
Technical support is available for purchase for the Java DB product through Sun.
Because Java DB and Derby have the same functionality, the Java DB documentation refers to the core functionality as Derby.
Java DB Version 10.5 is based on the Derby Version 10.5 release. References to "Derby" in the Java DB documentation refer to the Version 10.5 release of Apache Derby.
About this guide
For general information about the Derby documentation, such as a complete list of books, conventions, and further reading, see Getting Started with Java DB.
Purpose of this document
This book, the Java DB Reference Manual, provides reference information about Derby. It covers Derby's SQL language, the Derby implementation of JDBC, Derby system catalogs, Derby error messages, Derby properties, and SQL keywords.
Audience
This book is a reference for Derby users, typically application developers. Derby users who are not familiar with the SQL standard or the Java programming language will benefit from consulting books on those topics.
Derby users who want a how-to approach to working with Derby or an introduction to Derby concepts should read the Java DB Developer's Guide.
How this guide is organized
This guide includes the following sections:
 
SQL language reference
Reference information about Derby's SQL language, including manual pages for statements, functions, and other syntax elements.
 
SQL reserved words
SQL keywords beyond the standard SQL-92 keywords.
 
Derby support for SQL-92 features
A list of SQL-92 features that Derby does and does not support.
 
Derby system tables
Reference information about the Derby system catalogs.
 
Derby exception messages and SQL states
Information about Derby exception messages.
 
JDBC reference
Information about Derby's implementation of the Java Database Connectivity (JDBC) API.
 
Setting attributes for the database connection URL
Information about the supported attributes to Derby's JDBC database connection URL.
 
Derby property reference
Information about Derby properties.
 
J2EE Compliance: Java Transaction API and javax.sql Interfaces
Information about Derby's support for the Java EE platform, in particular support for the Java Transaction API and the JDBC API.
 
Derby API
Notes about proprietary APIs for Derby.
 
Supported territories
Territories supported by Derby.
 
Derby limitations
Limitations of Derby.
SQL language reference
Derby implements an SQL-92 core subset, as well as some SQL-99 features.
This section provides an overview of the current SQL language by describing the statements, built-in functions, data types, expressions, and special characters it contains.
Capitalization and special characters
Using the classes and methods of JDBC, you submit SQL statements to Derby as strings. The character set permitted for strings containing SQL statements is Unicode. Within these strings, the following rules apply:
 
Double quotation marks delimit special identifiers referred to in SQL-92 as delimited identifiers.
 
Single quotation marks delimit character strings.
 
Within a character string, to represent a single quotation mark or apostrophe, use two single quotation marks. (In other words, a single quotation mark is the escape character for a single quotation mark.)
A double quotation mark does not need an escape character. To represent a double quotation mark, simply use a double quotation mark. However, note that in a Java program, a double quotation mark requires the backslash escape character.
Example:
-- a single quotation mark is the escape character -- for a single quotation mark VALUES 'Joe''s umbrella' -- in ij, you don't need to escape the double quotation marks VALUES 'He said, "hello!"' n = stmt.executeUpdate( "UPDATE aTable setStringcol = 'He said, \"hello!\"'");
 
SQL keywords are case-insensitive. For example, you can type the keyword SELECT as SELECT, Select, select, or sELECT.
 
SQL-92-style identifiers are case-insensitive (see SQL92Identifier), unless they are delimited.
 
Java-style identifiers are always case-sensitive.
 
* is a wildcard within a SelectExpression. See The * wildcard. It can also be the multiplication operator. In all other cases, it is a syntactical metasymbol that flags items you can repeat 0 or more times.
 
% and _ are character wildcards when used within character strings following a LIKE operator (except when escaped with an escape character). See Boolean expressions.
 
Comments can be either single- or multiline as per the SQL-92 standard. Singleline comments start with two dashes (--) and end with the newline character. Multiline comments are bracketed and start with forward slash star (/*), and end with star forward slash (*/). Note that bracketed comments may be nested. Any text between the starting and ending comment character sequence is ignored.
SQL identifiers
An identifier is the representation within the language of items created by the user, as opposed to language keywords or commands. Some identifiers stand for dictionary objects, which are the objects you create- such as tables, views, indexes, columns, and constraints- that are stored in a database. They are called dictionary objects because Derby stores information about them in the system tables, sometimes known as a data dictionary. SQL also defines ways to alias these objects within certain statements.
Each kind of identifier must conform to a different set of rules. Identifiers representing dictionary objects must conform to SQL-92 identifier rules and are thus called SQL92Identifiers.
Rules for SQL92 identifiers
Ordinary identifiers are identifiers not surrounded by double quotation marks. Delimited identifiers are identifiers surrounded by double quotation marks.
An ordinary identifier must begin with a letter and contain only letters, underscore characters (_), and digits. The permitted letters and digits include all Unicode letters and digits, but Derby does not attempt to ensure that the characters in identifiers are valid in the database's locale.
A delimited identifier can contain any characters within the double quotation marks. The enclosing double quotation marks are not part of the identifier; they serve only to mark its beginning and end. Spaces at the end of a delimited identifier are insignificant (truncated). Derby translates two consecutive double quotation marks within a delimited identifier as one double quotation mark-that is, the "translated" double quotation mark becomes a character in the delimited identifier.
Periods within delimited identifiers are not separators but are part of the identifier (the name of the dictionary object being represented).
So, in the following example:
"A.B"
is a dictionary object, while
"A"."B"
is a dictionary object qualified by another dictionary object (such as a column named "B" within the table "A").
SQL92Identifier
An SQL92Identifier is a dictionary object identifier that conforms to the rules of SQL-92. SQL-92 states that identifiers for dictionary objects are limited to 128 characters and are case-insensitive (unless delimited by double quotes), because they are automatically translated into uppercase by the system. You cannot use reserved words as identifiers for dictionary objects unless they are delimited. If you attempt to use a name longer than 128 characters, SQLException X0X11 is raised.
Derby defines keywords beyond those specified by the SQL-92 standard (see SQL reserved words).
Example
-- the view name is stored in the -- system catalogs as ANIDENTIFIER CREATE VIEW AnIdentifier (RECEIVED) AS VALUES 1 -- the view name is stored in the system -- catalogs with case intact CREATE VIEW "ACaseSensitiveIdentifier" (RECEIVED) AS VALUES 1
This section describes the rules for using SQL92Identifiers to represent the following dictionary objects.
Qualifying dictionary objects
Since some dictionary objects can be contained within other objects, you can qualify those dictionary object names. Each component is separated from the next by a period. An SQL92Identifier is "dot-separated." You qualify a dictionary object name in order to avoid ambiguity.
column-Name
In many places in the SQL syntax, you can represent the name of a column by qualifying it with a table-Name or correlation-Name.
In some situations, you cannot qualify a column-Name with a table-Name or a correlation-Name, but must use a Simple-column-Name instead. Those situations are:
 
creating a table (CREATE TABLE statement)
 
specifying updatable columns in a cursor
 
in a column's correlation name in a SELECT expression (see SelectExpression)
 
in a column's correlation name in a TableExpression (see TableExpression)
You cannot use correlation-Names for updatable columns; using correlation-Names in this way will cause an SQL exception. For example:
SELECT c11 AS col1, c12 AS col2, c13 FROM t1 FOR UPDATE of c11,c13
In this example, the correlation-Name col1 FOR c11 is not permitted because c11 is listed in the FOR UPDATE list of columns. You can use the correlation-Name FOR c12 because it is not in the FOR UPDATE list.
Example
-- C.Country is a column-Name qualified with a -- correlation-Name. SELECT C.Country FROM APP.Countries C
correlation-Name
A correlation-Name is given to a table expression in a FROM clause as a new name or alias for that table. You do not qualify a correlation-Name with a schema-Name.
You cannot use correlation-Names for updatable columns; using correlation-Names in this way will cause an SQL exception. For example:
SELECT c11 AS col1, c12 AS col2, c13 FROM t1 FOR UPDATE of c11,c13
In this example, the correlation-Name col1 FOR c11 is not permitted because c11 is listed in the FOR UPDATE list of columns. You can use the correlation-Name FOR c12 because it is not in the FOR UPDATE list.
Example
-- C is a correlation-Name SELECT C.NAME FROM SAMP.STAFF C
new-table-Name
A new-table-Name represents a renamed table. You cannot qualify a new-table-Name with a schema-Name.
Example
-- FlightBooks is a new-table-Name that does not include a schema-Name RENAME TABLE FLIGHTAVAILABILITY TO FLIGHTAVAILABLE
schemaName
A schemaName represents a schema. Schemas contain other dictionary objects, such as tables and indexes. Schemas provide a way to name a subset of tables and other dictionary objects within a database.
You can explicitly create or drop a schema. The default user schema is the APP schema (if no user name is specified at connection time). You cannot create objects in schemas starting with SYS.
Thus, you can qualify references to tables with the schema name. When a schemaName is not specified, the default schema name is implicitly inserted. System tables are placed in the SYS schema. You must qualify all references to system tables with the SYS schema identifier. For more information about system tables, see Derby system tables.
A schema is hierarchically the highest level of dictionary object, so you cannot qualify a schemaName.
Syntax
SQL92Identifier
Example
-- SAMP.EMPLOYEE is a table-Name qualified by a schemaName SELECT COUNT(*) FROM SAMP.EMPLOYEE -- You must qualify system catalog names with their schema, SYS SELECT COUNT(*) FROM SYS.SysColumns
Simple-column-Name
A Simple-column-Name is used to represent a column when it cannot be qualified by a table-Name or correlation-Name. This is the case when the qualification is fixed, as it is in a column definition within a CREATE TABLE statement.
Example
-- country is a Simple-column-Name CREATE TABLE CONTINENT (COUNTRY VARCHAR(26) NOT NULL PRIMARY KEY, COUNTRY_ISO_CODE CHAR(2), REGION VARCHAR(26))
synonym-Name
A synonym-Name represents a synonym for a table or a view. You can qualify a synonym-Name with a schema-Name.
table-Name
A table-Name represents a table. You can qualify a table-Name with a schemaName.
Example
-- SAMP.PROJECT is a table-Name that includes a schemaName SELECT COUNT(*) FROM SAMP.PROJECT
view-Name
A view-Name represents a table or a view. You can qualify a view-Name with a schema-Name.
Example
-- This is a View qualified by a schema-Name SELECT COUNT(*) FROM SAMP.EMP_RESUME
index-Name
An index-Name represents an index. Indexes live in schemas, so you can qualify their names with schema-Names. Indexes on system tables are in the SYS schema.
Example
DROP INDEX APP.ORIGINDEX; -- OrigIndex is an index-Name without a schema-Name CREATE INDEX ORIGINDEX ON FLIGHTS (ORIG_AIRPORT)
constraint-Name
You cannot qualify constraint-names.
Example
-- country_fk2 is a constraint name CREATE TABLE DETAILED_MAPS (COUNTRY_ISO_CODE CHAR(2) CONSTRAINT country_fk2 REFERENCES COUNTRIES)
cursor-Name
A cursor-Name refers to a cursor. No SQL language command exists to assign a name to a cursor. Instead, you use the JDBC API to assign names to cursors or to retrieve system-generated names. For more information, see the Java DB Developer's Guide. If you assign a name to a cursor, you can refer to that name from within SQL statements.
You cannot qualify a cursor-Name.
Example
stmt.executeUpdate("UPDATE SAMP.STAFF SET COMM = " + "COMM + 20 " + "WHERE CURRENT OF " + ResultSet.getCursorName());
TriggerName
A TriggerName refers to a trigger created by a user.
Example
DROP TRIGGER TRIG1
AuthorizationIdentifier
User names within the Derby system are known as authorization identifiers. The authorization identifier represents the name of the user, if one has been provided in the connection request. The default schema for a user is equal to its authorization identifier. User names can be case-sensitive within the authentication system, but they are always case-insensitive within Derby's authorization system unless they are delimited. For more information, see the Java DB Developer's Guide.
Example
CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY( 'derby.database.fullAccessUsers', 'Amber,FRED')
RoleName
A RoleName refers to an SQL role. A role in a database is uniquely identified by its role name.
In terms of SQL, a role name is also technically an AuthorizationIdentifier, but that term is often used for user names in Derby for historical reasons.
Example
DROP ROLE reader
Statements
This section provides manual pages for both high-level language constructs and parts thereof. For example, the CREATE INDEX statement is a high-level statement that you can execute directly via the JDBC interface. This section also includes clauses, which are not high-level statements and which you cannot execute directly but only as part of a high-level statement. The ORDER BY and WHERE clauses are examples of this kind of clause. Finally, this section also includes some syntactically complex portions of statements called expressions, for example SelectExpression and TableSubquery. These clauses and expressions receive their own manual pages for ease of reference.
Unless it is explicitly stated otherwise, you can execute or prepare and then execute all the high-level statements, which are all marked with the word statement, via the interfaces provided by JDBC. This manual indicates whether an expression can be executed as a high-level statement.
The sections provide general information about statement use, and descriptions of the specific statements.
Interaction with the dependency system
Derby internally tracks the dependencies of prepared statements, which are SQL statements that are precompiled before being executed. Typically they are prepared (precompiled) once and executed multiple times.
Prepared statements depend on the dictionary objects and statements they reference. (Dictionary objects include tables, columns, constraints, indexes, views, and triggers.) Removing or modifying the dictionary objects or statements on which they depend invalidates them internally, which means that Derby will automatically try to recompile the statement when you execute it. If the statement fails to recompile, the execution request fails. However, if you take some action to restore the broken dependency (such as restoring the missing table), you can execute the same prepared statement, because Derby will recompile it automatically at the next execute request.
Statements depend on one another-an UPDATE WHERE CURRENT statement depends on the statement it references. Removing the statement on which it depends invalidates the UPDATE WHERE CURRENT statement.
In addition, prepared statements prevent execution of certain DDL statements if there are open results sets on them.
Manual pages for each statement detail what actions would invalidate that statement, if prepared.
Here is an example using the Derby tool ij:
ij> CREATE TABLE mytable (mycol INT); 0 rows inserted/updated/deleted ij> INSERT INTO mytable VALUES (1), (2), (3); 3 rows inserted/updated/deleted -- this example uses the ij command prepare, -- which prepares a statement ij> prepare p1 AS 'INSERT INTO MyTable VALUES (4)'; -- p1 depends on mytable; ij> execute p1; 1 row inserted/updated/deleted -- Derby executes it without recompiling ij> CREATE INDEX i1 ON mytable(mycol); 0 rows inserted/updated/deleted -- p1 is temporarily invalidated because of new index ij> execute p1; 1 row inserted/updated/deleted -- Derby automatically recompiles p1 and executes it ij> DROP TABLE mytable; 0 rows inserted/updated/deleted -- Derby permits you to drop table -- because result set of p1 is closed -- however, the statement p1 is temporarily invalidated ij> CREATE TABLE mytable (mycol INT); 0 rows inserted/updated/deleted ij> INSERT INTO mytable VALUES (1), (2), (3); 3 rows inserted/updated/deleted ij> execute p1; 1 row inserted/updated/deleted -- Because p1 is invalid, Derby tries to recompile it -- before executing. -- It is successful and executes. ij> DROP TABLE mytable; 0 rows inserted/updated/deleted -- statement p1 is now invalid, -- and this time the attempt to recompile it -- upon execution will fail ij> execute p1; ERROR 42X05: Table/View 'MYTABLE' does not exist.
ALTER TABLE statement
The ALTER TABLE statement allows you to:
 
add a column to a table
 
add a constraint to a table
 
drop a column from a table
 
drop an existing constraint from a table
 
increase the width of a VARCHAR or VARCHAR FOR BIT DATA column
 
override row-level locking for the table (or drop the override)
 
change the increment value and start value of the identity column
 
change the nullability constraint for a column
 
change the default value for a column
Syntax
ALTER TABLE table-Name { ADD COLUMN column-definition | ADD CONSTRAINT clause | DROP [ COLUMN ] column-name [ CASCADE | RESTRICT ] DROP { PRIMARY KEY | FOREIGN KEY constraint-name | UNIQUE constraint-name | CHECK constraint-name | CONSTRAINT constraint-name } ALTER [ COLUMN ] column-alteration | LOCKSIZE { ROW | TABLE } }
column-definition
Simple-column-Name [ DataType ] [ Column-level-constraint ]* [ [ WITH ] DEFAULT DefaultConstantExpression | generation-clause ]
The syntax for the column-definition for a new column is a subset of the syntax for a column in a CREATE TABLE statement.
The syntax of DataType is described in Data types. The DataType can be omitted only if you specify a generation-clause. If you omit the DataType, the type of the generated column is the type of the generation-clause. If you specify both a DataType and a generation-clause, the type of the generation-clause must be assignable to DataType.
For details on DefaultConstantExpression, see Column default.
column-alteration
column-Name SET DATA TYPE VARCHAR(integer) | column-Name SET DATA TYPE VARCHAR FOR BIT DATA(integer) | column-name SET INCREMENT BY integer-constant | column-name RESTART WITH integer-constant | column-name [ NOT ] NULL | column-name [ WITH | SET ] DEFAULT default-value | column-name DROP DEFAULT
In the column-alteration, SET INCREMENT BY integer-constant, specifies the interval between consecutive values of the identity column. The next value to be generated for the identity column will be determined from the last assigned value with the increment applied. The column must already be defined with the IDENTITY attribute.
RESTART WITH integer-constant specifies the next value to be generated for the identity column. RESTART WITH is useful for a table that has an identity column that was defined as GENERATED BY DEFAULT and that has a unique key defined on that identity column. Because GENERATED BY DEFAULT allows both manual inserts and system generated values, it is possible that manually inserted values can conflict with system generated values. To work around such conflicts, use the RESTART WITH syntax to specify the next value that will be generated for the identity column. Consider the following example, which involves a combination of automatically generated data and manually inserted data:
CREATE TABLE tauto(i INT GENERATED BY DEFAULT AS IDENTITY, k INT) CREATE UNIQUE INDEX tautoInd ON tauto(i) INSERT INTO tauto(k) values 1,2
The system will automatically generate values for the identity column.  But now you need to manually insert some data into the identity column:
INSERT INTO tauto VALUES (3,3) INSERT INTO tauto VALUES (4,4) INSERT INTO tauto VALUES (5,5)
The identity column has used values 1 through 5 at this point.  If you now want the system to generate a value, the system will generate a 3, which will result in a unique key exception because the value 3 has already been manually inserted.  To compensate for the manual inserts, issue an ALTER TABLE statement for the identity column with RESTART WITH 6:
ALTER TABLE tauto ALTER COLUMN i RESTART WITH 6
ALTER TABLE does not affect any view that references the table being altered. This includes views that have an "*" in their SELECT list. You must drop and re-create those views if you wish them to return the new columns.
Derby raises an error if you try to change the DataType of a generated column to a type which is not assignable from the type of the generation-clause. Derby also raises an error if you try to add a DEFAULT clause to a generated column.
Adding columns
The syntax for the column-definition for a new column is almost the same as for a column in a CREATE TABLE statement. This syntax allows a column constraint to be placed on the new column within the ALTER TABLE ADD COLUMN statement. However, a column with a NOT NULL constraint can be added to an existing table if you give a default value; otherwise, an exception is thrown when the ALTER TABLE statement is executed.
Just as in CREATE TABLE, if the column definition includes a primary key constraint, the column cannot contain null values, so the NOT NULL attribute must also be specified (SQLSTATE 42831).
Note: If a table has an UPDATE trigger without an explicit column list, adding a column to that table in effect adds that column to the implicit update column list upon which the trigger is defined, and all references to transition variables are invalidated so that they pick up the new column.
If you add a generated column to a table, Derby computes the generated values for all existing rows in the table.
Adding constraints
ALTER TABLE ADD CONSTRAINT adds a table-level constraint to an existing table. Any supported table-level constraint type can be added via ALTER TABLE. The following limitations exist on adding a constraint to an existing table:
 
When adding a foreign key or check constraint to an existing table, Derby checks the table to make sure existing rows satisfy the constraint. If any row is invalid, Derby throws a statement exception and the constraint is not added.
 
All columns included in a primary key must contain non null data and be unique.
ALTER TABLE ADD UNIQUE or PRIMARY KEY provide a shorthand method of defining a primary key composed of a single column. If PRIMARY KEY is specified in the definition of column C, the effect is the same as if the PRIMARY KEY(C) clause were specified as a separate clause. The column cannot contain null values, so the NOT NULL attribute must also be specified.
For information on the syntax of constraints, see CONSTRAINT clause. Use the syntax for table-level constraint when adding a constraint with the ADD TABLE ADD CONSTRAINT syntax.
Dropping columns
ALTER TABLE DROP COLUMN allows you to drop a column from a table.
The keyword COLUMN is optional.
The keywords CASCADE and RESTRICT are also optional. If you specify neither CASCADE nor RESTRICT, the default is CASCADE.
If you specify RESTRICT, then the column drop will be rejected if it would cause a dependent schema object to become invalid.
If you specify CASCADE, then the column drop should additionally drop other schema objects which have become invalid.
The schema objects which can cause a DROP COLUMN RESTRICT to be rejected include: views, triggers, primary key constraints, foreign key constraints, unique key constraints, check constraints, and column privileges. If one of these types of objects depends on the column being dropped, DROP COLUMN RESTRICT will reject the statement.
Derby also raises an error if you specify RESTRICT when you drop a column referenced by the generation-clause of a generated column. However, if you specify CASCADE, the generated column is also dropped with CASCADE semantics.
You may not drop the last (only) column in a table.
CASCADE/RESTRICT doesn't consider whether the column being dropped is used in any indexes. When a column is dropped, it is removed from any indexes which contain it. If that column was the only column in the index, the entire index is dropped.
Dropping constraints
ALTER TABLE DROP CONSTRAINT drops a constraint on an existing table. To drop an unnamed constraint, you must specify the generated constraint name stored in SYS.SYSCONSTRAINTS as a delimited identifier.
Dropping a primary key, unique, or foreign key constraint drops the physical index that enforces the constraint (also known as a backing index).
Modifying columns
The column-alteration allows you to alter the named column in the following ways:
 
Increasing the width of an existing VARCHAR or VARCHAR FOR BIT DATA column. CHARACTER VARYING or CHAR VARYING can be used as synonyms for the VARCHAR keyword.
To increase the width of a column of these types, specify the data type and new size after the column name.
You are not allowed to decrease the width or to change the data type. You are not allowed to increase the width of a column that is part of a primary or unique key referenced by a foreign key constraint or that is part of a foreign key constraint.
 
Specifying the interval between consecutive values of the identity column.
To set an interval between consecutive values of the identity column, specify the integer-constant. You must previously define the column with the IDENTITY attribute (SQLSTATE 42837). If there are existing rows in the table, the values in the column for which the SET INCREMENT default was added do not change.
 
Modifying the nullability constraint of a column.
You can add the NOT NULL constraint to an existing column. To do so there must not be existing NULL values for the column in the table.
You can remove the NOT NULL constraint from an existing column. To do so the column must not be used in a PRIMARY KEY constraint.
 
Changing the default value for a column.
You can use DEFAULT default-value to change a column default. To disable a previously set default, use DROP DEFAULT (alternatively, you can specify NULL as the default-value).
Setting defaults
You can specify a default value for a new column. A default value is the value that is inserted into a column if no other value is specified. If not explicitly specified, the default value of a column is NULL. If you add a default to a new column, existing rows in the table gain the default value in the new column.
For more information about defaults, see CREATE TABLE statement.
Changing the lock granularity for the table
The LOCKSIZE clause allows you to override row-level locking for the specific table, if your system uses the default setting of row-level locking. (If your system is set for table-level locking, you cannot change the locking granularity to row-level locking, although Derby allows you to use the LOCKSIZE clause in such a situation without throwing an exception.) To override row-level locking for the specific table, set locking for the table to TABLE. If you created the table with table-level locking granularity, you can change locking back to ROW with the LOCKSIZE clause in the ALTER TABLE STATEMENT. For information about why this is sometimes useful, see Tuning Java DB.
Examples
-- Add a new column with a column-level constraint -- to an existing table -- An exception will be thrown if the table -- contains any rows -- since the newcol will be initialized to NULL -- in all existing rows in the table ALTER TABLE CITIES ADD COLUMN REGION VARCHAR(26) CONSTRAINT NEW_CONSTRAINT CHECK (REGION IS NOT NULL); -- Add a new unique constraint to an existing table -- An exception will be thrown if duplicate keys are found ALTER TABLE SAMP.DEPARTMENT ADD CONSTRAINT NEW_UNIQUE UNIQUE (DEPTNO); -- add a new foreign key constraint to the -- Cities table. Each row in Cities is checked -- to make sure it satisfied the constraints. -- if any rows don't satisfy the constraint, the -- constraint is not added ALTER TABLE CITIES ADD CONSTRAINT COUNTRY_FK Foreign Key (COUNTRY) REFERENCES COUNTRIES (COUNTRY); -- Add a primary key constraint to a table -- First, create a new table CREATE TABLE ACTIVITIES (CITY_ID INT NOT NULL, SEASON CHAR(2), ACTIVITY VARCHAR(32) NOT NULL); -- You will not be able to add this constraint if the -- columns you are including in the primary key have -- null data or duplicate values. ALTER TABLE Activities ADD PRIMARY KEY (city_id, activity); -- Drop the city_id column if there are no dependent objects: ALTER TABLE Cities DROP COLUMN city_id RESTRICT; -- Drop the city_id column, also dropping all dependent objects: ALTER TABLE Cities DROP COLUMN city_id CASCADE; -- Drop a primary key constraint from the CITIES table ALTER TABLE Cities DROP CONSTRAINT Cities_PK; -- Drop a foreign key constraint from the CITIES table ALTER TABLE Cities DROP CONSTRAINT COUNTRIES_FK; -- add a DEPTNO column with a default value of 1 ALTER TABLE SAMP.EMP_ACT ADD COLUMN DEPTNO INT DEFAULT 1; -- increase the width of a VARCHAR column ALTER TABLE SAMP.EMP_PHOTO ALTER PHOTO_FORMAT SET DATA TYPE VARCHAR(30); -- change the lock granularity of a table ALTER TABLE SAMP.SALES LOCKSIZE TABLE; -- Remove the NOT NULL constraint from the MANAGER column ALTER TABLE Employees ALTER COLUMN Manager NULL; -- Add the NOT NULL constraint to the SSN column ALTER TABLE Employees ALTER COLUMN ssn NOT NULL; -- Change the default value for the SALARY column ALTER TABLE Employees ALTER COLUMN Salary DEFAULT 1000.0 ALTER TABLE Employees ALTER COLUMN Salary DROP DEFAULT
Results
An ALTER TABLE statement causes all statements that are dependent on the table being altered to be recompiled before their next execution. ALTER TABLE is not allowed if there are any open cursors that reference the table being altered.
CALL (PROCEDURE) statement
The CALL (PROCEDURE) statement is used to call procedures. A call to a procedure does not return any value.
Syntax
CALL procedure-Name ( [ expression [, expression]* ] )
Example
CREATE PROCEDURE SALES.TOTAL_REVENUE(IN S_MONTH INTEGER, IN S_YEAR INTEGER, OUT TOTAL DECIMAL(10,2)) PARAMETER STYLE JAVA READS SQL DATA LANGUAGE JAVA EXTERNAL NAME 'com.acme.sales.calculateRevenueByMonth'; CALL SALES.TOTAL_REVENUE(?,?,?);
CREATE statements
Use the CREATE statements to create functions, indexes, procedures, roles, schemas, synonyms, tables, triggers, and views.
CREATE FUNCTION statement
The CREATE FUNCTION statement allows you to create Java functions, which you can then use in an expression.
The function owner and the database owner automatically gain the EXECUTE privilege on the function, and are able to grant this privilege to other users. The EXECUTE privileges cannot be revoked from the function and database owners.
For details on how Derby matches functions to Java methods, see Argument matching.
Syntax
function-Name
If schema-Name is not provided, the current schema is the default schema. If a qualified procedure name is specified, the schema name cannot begin with SYS.
FunctionParameter
[ parameter-Name ] DataType
PararameterName must be unique within a function.
The syntax of DataType is described in Data types.
Note: Data-types such as BLOB, CLOB, LONG VARCHAR, LONG VARCHAR FOR BIT DATA, and XML are not allowed as parameters in a CREATE FUNCTION statement.
ReturnDataType
TableType | DataType
The syntax of DataType is described in Data types.
TableType
This is the return type of a table function. Currently, only Derby-style table functions are supported. They are functions which return JDBC ResultSets. For more information, see "Programming Derby-style table functions" in the Java DB Developer's Guide.
At run-time, as values are read out of the user-supplied ResultSet, Derby coerces those values to the data types declared in the CREATE FUNCTION statement. This affects values typed as CHAR, VARCHAR, LONG VARCHAR, CHAR FOR BIT DATA, VARCHAR FOR BIT DATA, LONG VARCHAR FOR BIT DATA, and DECIMAL/NUMERIC. Values which are too long are truncated to the maximum length declared in the CREATE FUNCTION statement. In addition, if a String value is returned in the ResultSet for a column of CHAR type and the String is shorter than the declared length of the CHAR column, Derby pads the end of the String with blanks in order to stretch it out to the declared length.
ColumnElement
The syntax of DataType is described in Data types.
Note: XML is not allowed as the type of a column in the dataset returned by a table function.
FunctionElement
{ | LANGUAGE { JAVA } | DeterministicCharacteristic | EXTERNAL NAME string | PARAMETER STYLE ParameterStyle | { NO SQL | CONTAINS SQL | READS SQL DATA } | { RETURNS NULL ON NULL INPUT | CALLED ON NULL INPUT } }
LANGUAGE
JAVA- the database manager will call the function as a public static method in a Java class.
EXTERNAL NAME string
String describes the Java method to be called when the function is executed, and takes the following form:
class_name.method_name
The External Name cannot have any extraneous spaces.
DeterministicCharacteristic
DETERMINISTIC | NOT DETERMINISTIC
Declares that the function is deterministic, meaning that with the same set of input values, it always computes the same result. The default is NOT DETERMINISTIC. Derby cannot recognize whether an operation is actually deterministic, so you must take care to specify the DeterministicCharacteristic correctly.
ParameterStyle
JAVA | DERBY_JDBC_RESULT_SET
The function will use a parameter-passing convention that conforms to the Java language and SQL Routines specification. INOUT and OUT parameters will be passed as single entry arrays to facilitate returning values. Result sets can be returned through additional parameters to the Java method of type java.sql.ResultSet[] that are passed single entry arrays.
Derby does not support long column types (for example Long Varchar, BLOB, and so on). An error will occur if you try to use one of these long column types.
The PARAMETER STYLE is DERBY_JDBC_RESULT_SET if and only if this is a Derby-style table function, that is, a function which returns TableType and which is mapped to a method which returns a JDBC ResultSet. Otherwise, the PARAMETER STYLE must be JAVA.
NO SQL, CONTAINS SQL, READS SQL DATA
Indicates whether the function issues any SQL statements and, if so, what type.
CONTAINS SQL
Indicates that SQL statements that neither read nor modify SQL data can be executed by the function. Statements that are not supported in any function return a different error.
NO SQL
Indicates that the function cannot execute any SQL statements
READS SQL DATA
Indicates that some SQL statements that do not modify SQL data can be included in the function. Statements that are not supported in any stored function return a different error. This is the default value.
RETURNS NULL ON NULL INPUT or CALLED ON NULL INPUT
Specifies whether the function is called if any of the input arguments is null. The result is the null value.
RETURNS NULL ON NULL INPUT
Specifies that the function is not invoked if any of the input arguments is null. The result is the null value.
CALLED ON NULL INPUT
Specifies that the function is invoked if any or all input arguments are null. This specification means that the function must be coded to test for null argument values. The function can return a null or non-null value. This is the default setting.
The function elements may appear in any order, but each type of element can only appear once. A function definition must contain these elements:
 
LANGUAGE
 
PARAMETER STYLE
 
EXTERNAL NAME
Example of declaring a scalar function
CREATE FUNCTION TO_DEGREES ( RADIANS DOUBLE ) RETURNS DOUBLE PARAMETER STYLE JAVA NO SQL LANGUAGE JAVA EXTERNAL NAME 'java.lang.Math.toDegrees'
Example of declaring a table function
CREATE FUNCTION PROPERTY_FILE_READER ( FILENAME VARCHAR( 32672 ) ) RETURNS TABLE ( KEY_COL VARCHAR( 10 ), VALUE_COL VARCHAR( 1000 ) ) LANGUAGE JAVA PARAMETER STYLE DERBY_JDBC_RESULT_SET NO SQL EXTERNAL NAME 'vtis.example.PropertyFileVTI.propertyFileVTI'
CREATE INDEX statement
A CREATE INDEX statement creates an index on a table. Indexes can be on one or more columns in the table.
Syntax
CREATE [UNIQUE] INDEX index-Name ON table-Name ( Simple-column-Name [ ASC | DESC ] [ , Simple-column-Name [ ASC | DESC ]] * )
The maximum number of columns for an index key in Derby is 16.
An index name cannot exceed 128 characters.
A column must not be named more than once in a single CREATE INDEX statement. Different indexes can name the same column, however.
Derby can use indexes to improve the performance of data manipulation statements (see Tuning Java DB). In addition, UNIQUE indexes provide a form of data integrity checking.
Index names are unique within a schema. (Some database systems allow different tables in a single schema to have indexes of the same name, but Derby does not.) Both index and table are assumed to be in the same schema if a schema name is specified for one of the names, but not the other. If schema names are specified for both index and table, an exception will be thrown if the schema names are not the same. If no schema name is specified for either table or index, the current schema is used.
By default, Derby uses the ascending order of each column to create the index. Specifying ASC after the column name does not alter the default behavior. The DESC keyword after the column name causes Derby to use descending order for the column to create the index. Using the descending order for a column can help improve the performance of queries that require the results in mixed sort order or descending order and for queries that select the minimum or maximum value of an indexed column.
If a qualified index name is specified, the schema name cannot begin with SYS.
Indexes and constraints
Unique, primary key, and foreign key constraints generate indexes that enforce or "back" the constraint (and are thus sometimes called backing indexes). If a column or set of columns has a UNIQUE or PRIMARY KEY constraint on it, you can not create an index on those columns. Derby has already created it for you with a system-generated name. System-generated names for indexes that back up constraints are easy to find by querying the system tables if you name your constraint. Adding a PRIMARY KEY or UNIQUE constraint when an existing UNIQUE index exists on the same set of columns will result in two physical indexes on the table for the same set of columns. One index is the original UNIQUE index and one is the backing index for the new constraint.
To find out the name of the index that backs a constraint called FLIGHTS_PK:
SELECT CONGLOMERATENAME FROM SYS.SYSCONGLOMERATES, SYS.SYSCONSTRAINTS WHERE SYS.SYSCONGLOMERATES.TABLEID = SYSCONSTRAINTS.TABLEID AND CONSTRAINTNAME = 'FLIGHTS_PK'
CREATE INDEX OrigIndex ON Flights(orig_airport); -- money is usually ordered from greatest to least, -- so create the index using the descending order CREATE INDEX PAY_DESC ON SAMP.EMPLOYEE (SALARY); -- use a larger page size for the index call SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY('derby.storage.pageSize','8192'); CREATE INDEX IXSALE ON SAMP.SALES (SALES); call SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY('derby.storage.pageSize',NULL);
Page size and key size
Note: The size of the key columns in an index must be equal to or smaller than half the page size. If the length of the key columns in an existing row in a table is larger than half the page size of the index, creating an index on those key columns for the table will fail. This error only occurs when creating an index if an existing row in the table fails the criteria. After an index is created, inserts may fail if the size of their associated key exceeds the criteria.
Statement dependency system
Prepared statements that involve SELECT, INSERT, UPDATE, UPDATE WHERE CURRENT, DELETE, and DELETE WHERE CURRENT on the table referenced by the CREATE INDEX statement are invalidated when the index is created. Open cursors on the table are not affected.
CREATE PROCEDURE statement
The CREATE PROCEDURE statement allows you to create Java stored procedures, which you can then call using the CALL PROCEDURE statement.
The procedure owner and the database owner automatically gain the EXECUTE privilege on the procedure, and are able to grant this privilege to other users. The EXECUTE privileges cannot be revoked from the procedure and database owners.
For details on how Derby matches procedures to Java methods, see Argument matching.
Syntax
procedure-Name
If schema-Name is not provided, the current schema is the default schema. If a qualified procedure name is specified, the schema name cannot begin with SYS.
ProcedureParameter
[ { IN | OUT | INOUT } ] [ parameter-Name ] DataType
The default value for a parameter is IN. ParameterName must be unique within a procedure.
The syntax of DataType is described in Data types.
Note: Data-types such as BLOB, CLOB, LONG VARCHAR, LONG VARCHAR FOR BIT DATA, and XML are not allowed as parameters in a CREATE PROCEDURE statement.
ProcedureElement
{ | [ DYNAMIC ] RESULT SETS INTEGER | LANGUAGE { JAVA } | DeterministicCharacteristic | EXTERNAL NAME string | PARAMETER STYLE JAVA | { NO SQL | MODIFIES SQL DATA | CONTAINS SQL | READS SQL DATA } }
DYNAMIC RESULT SETS integer
Indicates the estimated upper bound of returned result sets for the procedure. Default is no (zero) dynamic result sets.
LANGUAGE
JAVA- the database manager will call the procedure as a public static method in a Java class.
EXTERNAL NAME string
String describes the Java method to be called when the procedure is executed, and takes the following form:
class_name.method_name
The External Name cannot have any extraneous spaces.
DeterministicCharacteristic
DETERMINISTIC | NOT DETERMINISTIC
Declares that the procedure is deterministic, meaning that with the same set of input values, it always computes the same result. The default is NOT DETERMINISTIC. Derby cannot recognize whether an operation is actually deterministic, so you must take care to specify the DeterministicCharacteristic correctly.
PARAMETER STYLE
JAVA - The procedure will use a parameter-passing convention that conforms to the Java language and SQL Routines specification. INOUT and OUT parameters will be passed as single entry arrays to facilitate returning values. Result sets are returned through additional parameters to the Java method of type java.sql.ResultSet [] that are passed single entry arrays.
Derby does not support long column types (for example Long Varchar, BLOB, and so on). An error will occur if you try to use one of these long column types.
NO SQL, CONTAINS SQL, READS SQL DATA, MODIFIES SQL DATA
Indicates whether the stored procedure issues any SQL statements and, if so, what type.
CONTAINS SQL
Indicates that SQL statements that neither read nor modify SQL data can be executed by the stored procedure. Statements that are not supported in any stored procedure return a different error. MODIFIES SQL DATA is the default value.
NO SQL
Indicates that the stored procedure cannot execute any SQL statements
READS SQL DATA
Indicates that some SQL statements that do not modify SQL data can be included in the stored procedure. Statements that are not supported in any stored procedure return a different error.
MODIFIES SQL DATA
Indicates that the stored procedure can execute any SQL statement except statements that are not supported in stored procedures.
The procedure elements may appear in any order, but each type of element can only appear once. A procedure definition must contain these elements:
 
LANGUAGE
 
PARAMETER STYLE
 
EXTERNAL NAME
Example
CREATE PROCEDURE SALES.TOTAL_REVENUE(IN S_MONTH INTEGER, IN S_YEAR INTEGER, OUT TOTAL DECIMAL(10,2)) PARAMETER STYLE JAVA READS SQL DATA LANGUAGE JAVA EXTERNAL NAME 'com.acme.sales.calculateRevenueByMonth'
CREATE ROLE statement
The CREATE ROLE statement allows you to create an SQL role.
Only the database owner can create a role.
For more information on roles, see "Using SQL roles" in the Java DB Developer's Guide.
Syntax
CREATE ROLE roleName
Before you issue a CREATE ROLE statement, verify that the derby.database.sqlAuthorization property is set to TRUE. The derby.database.sqlAuthorization property enables SQL authorization mode.
You cannot create a role name if there is a user by that name. An attempt to create a role name that conflicts with an existing user name raises the SQLException X0Y68.
If user names are not controlled by the database owner (or administrator), it may be a good idea to use a naming convention for roles to reduce the possibility of collision with user names.
Derby tries to avoid name collision between user names and role names, but this is not always possible, because Derby has a pluggable authorization architecture. For example, an externally defined user may exist who has never yet connected to the database, created any schema objects, or been granted any privileges. If Derby knows about a user name, it will forbid creating a role with that name. Correspondingly, a user who has the same name as a role will not be allowed to connect. Derby built-in users are checked for collision when a role is created.
A role name cannot start with the prefix SYS (after case normalization). The purpose of this restriction is to reserve a name space for system-defined roles at a later point. Use of the prefix SYS raises the SQLException 4293A.
You cannot create a role with the name PUBLIC (after case normalization). PUBLIC is a reserved authorization identifier. An attempt to create a role with the name PUBLIC raises SQLException 4251B.
Example of creating a role
CREATE ROLE purchases_reader;
Examples of invalid role names
CREATE ROLE public; -- throws SQLException; CREATE ROLE "PUBLIC"; -- throws SQLException; CREATE ROLE sysrole; -- throws SQLException;
Example of creating a role using a naming convention
The following example uses the convention of giving every role name the suffix _role.
CREATE ROLE purchases_reader_role;
CREATE SCHEMA statement
A schema is a way to logically group objects in a single collection and provide a unique namespace for objects.
Syntax
CREATE SCHEMA { [ schemaName AUTHORIZATION user-name ] | [ schemaName ] | [ AUTHORIZATION user-name ] }
The CREATE SCHEMA statement is used to create a schema. A schema name cannot exceed 128 characters. Schema names must be unique within the database.
The CREATE SCHEMA statement is subject to access control when the derby.database.sqlAuthorization property is set to true for the database or system. Only the database owner can create a schema with a name different from the current user name, and only the the database owner can specify
AUTHORIZATION user-name
with a user name other than the current user name. See "derby.database.sqlAuthorization" for information about the derby.database.sqlAuthorization property.
Note: Although the SQL standard allows you to specify any AuthorizationIdentifier as an AUTHORIZATION argument, Derby allows you to specify only a user, not a role.
CREATE SCHEMA examples
To create a schema for airline-related tables and give the authorization ID anita access to all of the objects that use the schema, use the following syntax:
CREATE SCHEMA FLIGHTS AUTHORIZATION anita
To create a schema employee-related tables, use the following syntax:
CREATE SCHEMA EMP
To create a schema that uses the same name as the authorization ID takumi, use the following syntax:
CREATE SCHEMA AUTHORIZATION takumi
To create a table called availability in the EMP and FLIGHTS schemas, use the following syntax:
CREATE TABLE FLIGHTS.AVAILABILITY (FLIGHT_ID CHAR(6) NOT NULL, SEGMENT_NUMBER INT NOT NULL, FLIGHT_DATE DATE NOT NULL, ECONOMY_SEATS_TAKEN INT, BUSINESS_SEATS_TAKEN INT, FIRSTCLASS_SEATS_TAKEN INT, CONSTRAINT FLT_AVAIL_PK PRIMARY KEY (FLIGHT_ID, SEGMENT_NUMBER, FLIGHT_DATE))
CREATE TABLE EMP.AVAILABILITY (HOTEL_ID INT NOT NULL, BOOKING_DATE DATE NOT NULL, ROOMS_TAKEN INT, CONSTRAINT HOTELAVAIL_PK PRIMARY KEY (HOTEL_ID, BOOKING_DATE))
CREATE SYNONYM statement
Use the CREATE SYNONYM statement to provide an alternate name for a table or a view that is present in the same schema or another schema. You can also create synonyms for other synonyms, resulting in nested synonyms. A synonym can be used instead of the original qualified table or view name in SELECT, INSERT, UPDATE, DELETE or LOCK TABLE statements. You can create a synonym for a table or a view that doesn't exist, but the target table or view must be present before the synonym can be used.
Synonyms share the same namespace as tables or views. You cannot create a synonym with the same name as a table that already exists in the same schema. Similarly, you cannot create a table or view with a name that matches a synonym already present.
A synonym can be defined for a table/view that does not exist when you create the synonym. If the table or view doesn't exist, you will receive a warning message (SQLSTATE 01522). The referenced object must be present when you use a synonym in a DML statement.
You can create a nested synonym (a synonym for another synonym), but any attempt to create a synonym that results in a circular reference will return an error message (SQLSTATE 42916).
Synonyms cannot be defined in system schemas. All schemas starting with 'SYS' are considered system schemas and are reserved by Derby.
A synonym cannot be defined on a temporary table. Attempting to define a synonym on a temporary table will return an error message (SQLSTATE XCL51).
Syntax
CREATE SYNONYM synonym-Name FOR { view-Name | table-Name }
The synonym-Name in the statement represents the synonym name you are giving the target table or view, while the view-Name or table-Name represents the original name of the target table or view.
Example
CREATE SYNONYM SAMP.T1 FOR SAMP.TABLEWITHLONGNAME
CREATE TABLE statement
A CREATE TABLE statement creates a table. Tables contain columns and constraints, rules to which data must conform. Table-level constraints specify a column or columns. Columns have a data type and can specify column constraints (column-level constraints).
The table owner and the database owner automatically gain the following privileges on the table and are able to grant these privileges to other users:
 
INSERT
 
SELECT
 
REFERENCES
 
TRIGGER
 
UPDATE
These privileges cannot be revoked from the table and database owners.
For information about constraints, see CONSTRAINT clause.
You can specify a default value for a column. A default value is the value to be inserted into a column if no other value is specified. If not explicitly specified, the default value of a column is NULL. See Column default.
You can specify storage properties such as page size for a table by calling the SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY system procedure.
If a qualified table name is specified, the schema name cannot begin with SYS.
Syntax
There are two different variants of the CREATE TABLE statement, depending on whether you are specifying the column definitions and constraints, or whether you are modeling the columns after the results of a query expression:
CREATE TABLE table-Name { ( {column-definition | Table-level constraint} [ , {column-definition | Table-level constraint} ] * ) | [ ( column-name [ , column-name ] * ) ] AS query-expression WITH NO DATA }
Example
CREATE TABLE HOTELAVAILABILITY (HOTEL_ID INT NOT NULL, BOOKING_DATE DATE NOT NULL, ROOMS_TAKEN INT DEFAULT 0, PRIMARY KEY (HOTEL_ID, BOOKING_DATE)); -- the table-level primary key definition allows you to -- include two columns in the primary key definition PRIMARY KEY (hotel_id, booking_date)) -- assign an identity column attribute to an INTEGER -- column, and also define a primary key constraint -- on the column CREATE TABLE PEOPLE (PERSON_ID INT NOT NULL GENERATED ALWAYS AS IDENTITY CONSTRAINT PEOPLE_PK PRIMARY KEY, PERSON VARCHAR(26)); -- assign an identity column attribute to a SMALLINT -- column with an initial value of 5 and an increment value -- of 5. CREATE TABLE GROUPS (GROUP_ID SMALLINT NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 5, INCREMENT BY 5), ADDRESS VARCHAR(100), PHONE VARCHAR(15));
Note: For more examples of CREATE TABLE statements using the various constraints, see CONSTRAINT clause.
CREATE TABLE ... AS ...
With the alternate form of the CREATE TABLE statement, the column names and/or the column data types can be specified by providing a query. The columns in the query result are used as a model for creating the columns in the new table.
If no column names are specified for the new table, then all the columns in the result of the query expression are used to create same-named columns in the new table, of the corresponding data type(s). If one or more column names are specified for the new table, then the same number of columns must be present in the result of the query expression; the data types of those columns are used for the corresponding columns of the new table.
The WITH NO DATA clause specifies that the data rows which result from evaluating the query expression are not used; only the names and data types of the columns in the query result are used. The WITH NO DATA clause must be specified; in a future release, Derby may be modified to allow the WITH DATA clause to be provided, which would indicate that the results of the query expression should be inserted into the newly-created table. In the current release, however, only the WITH NO DATA form of the statement is accepted.
Example
-- create a new table using all the columns and data types -- from an existing table: CREATE TABLE T3 AS SELECT * FROM T1 WITH NO DATA; -- create a new table, providing new names for the columns, but -- using the data types from the columns of an existing table: CREATE TABLE T3 (A,B,C,D,E) AS SELECT * FROM T1 WITH NO DATA; -- create a new table, providing new names for the columns, -- using the data types from the indicated columns of an existing table: CREATE TABLE T3 (A,B,C) AS SELECT V,DP,I FROM T1 WITH NO DATA; -- This example shows that the columns in the result of the -- query expression may be unnamed expressions, but their data -- types can still be used to provide the data types for the -- corresponding named columns in the newly-created table: CREATE TABLE T3 (X,Y) AS SELECT 2*I,2.0*F FROM T1 WITH NO DATA;
column-definition:
Simple-column-Name [ DataType ] [ Column-level-constraint ]* [ [ WITH ] DEFAULT DefaultConstantExpression | generated-column-spec | generation-clause ] [ Column-level-constraint ]*
The syntax of DataType is described in Data types. The DataType can be omitted only if you specify a generation-clause. If you omit the DataType, the type of the generated column is the type of the generation-clause. If you specify both a DataType and a generation-clause, the type of the generation-clause must be assignable to DataType.
Column default
For the definition of a default value, a DefaultConstantExpression is an expression that does not refer to any table. It can include constants, date-time special registers, current schemas, users, roles, and null:
DefaultConstantExpression: NULL | CURRENT { SCHEMA | SQLID } | USER | CURRENT_USER | SESSION_USER | CURRENT_ROLE | DATE | TIME | TIMESTAMP | CURRENT DATE | CURRENT_DATE | CURRENT TIME | CURRENT_TIME | CURRENT TIMESTAMP | CURRENT_TIMESTAMP | literal
For details about Derby literal values, see Data types.
The values in a DefaultConstantExpression must be compatible in type with the column, but a DefaultConstantExpression has the following additional type restrictions:
 
If you specify USER, CURRENT_USER, SESSION_USER, or CURRENT_ROLE, the column must be a character column whose length is at least 8.
 
If you specify CURRENT SCHEMA or CURRENT SQLID, the column must be a character column whose length is at least 128.
 
If the column is an integer type, the default value must be an integer literal.
 
If the column is a decimal type, the scale and precision of the default value must be within those of the column.
generated-column-spec:
[ GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( START WITH IntegerConstant [ ,INCREMENT BY IntegerConstant] ) ] ] ]
Identity column attributes
A table can have at most one identity column.
For SMALLINT, INT, and BIGINT columns with identity attributes, Derby automatically assigns increasing integer values to the column. Identity column attributes behave like other defaults in that when an insert statement does not specify a value for the column, Derby automatically provides the value. However, the value is not a constant; Derby automatically increments the default value at insertion time.
The IDENTITY keyword can only be specified if the data type associated with the column is one of the following exact integer types.
 
SMALLINT
 
INT
 
BIGINT
There are two kinds of identity columns in Derby: those which are GENERATED ALWAYS and those which are GENERATED BY DEFAULT.
GENERATED ALWAYS
An identity column that is GENERATED ALWAYS will increment the default value on every insertion and will store the incremented value into the column. Unlike other defaults, you cannot insert a value directly into or update an identity column that is GENERATED ALWAYS. Instead, either specify the DEFAULT keyword when inserting into the identity column, or leave the identity column out of the insertion column list altogether. For example:
create table greetings (i int generated always as identity, ch char(50)); insert into greetings values (DEFAULT, 'hello'); insert into greetings(ch) values ('bonjour');
Automatically generated values in a GENERATED ALWAYS identity column are unique. Creating an identity column does not create an index on the column.
GENERATED BY DEFAULT
An identity column that is GENERATED BY DEFAULT will only increment and use the default value on insertions when no explicit value is given. Unlike GENERATED ALWAYS columns, you can specify a particular value in an insertion statement to be used instead of the generated default value.
To use the generated default, either specify the DEFAULT keyword when inserting into the identity column, or just leave the identity column out of the insertion column list. To specify a value, included it in the insertion statement. For example:
create table greetings (i int generated by default as identity, ch char(50)); -- specify value "1": insert into greetings values (1, 'hi'); -- use generated default insert into greetings values (DEFAULT, 'salut'); -- use generated default insert into greetings(ch) values ('bonjour');
Note that unlike a GENERATED ALWAYS column, a GENERATED BY DEFAULT column does not guarantee uniqueness. Thus, in the above example, the hi and salut rows will both have an identity value of "1", because the generated column starts at "1" and the user-specified value was also "1". To prevent duplication, especially when loading or importing data, create the table using the START WITH value which corresponds to the first identity value that the system should assign. To check for this condition and disallow it, you can use a primary key or unique constraint on the GENERATED BY DEFAULT identity column.
By default, the initial value of an identity column is 1, and the amount of the increment is 1. You can specify non-default values for both the initial value and the interval amount when you define the column with the key words START WITH and INCREMENT BY. And if you specify a negative number for the increment value, Derbydecrements the value with each insert. If this value is positive, Derby increments the value with each insert. A value of 0 raises a statement exception.
The maximum and minimum values allowed in identity columns are determined by the data type of the column. Attempting to insert a value outside the range of values supported by the data type raises an exception.
Table 1. Maximum and Minimum Values for Columns with Generated Column Specs
Data type
Maximum Value
Minimum Value
SMALLINT
32767 (java.lang.Short.MAX_VALUE)
-32768 (java.lang.Short.MIN_VALUE)
INT
2147483647 (java.lang.Integer.MAX_VALUE)
-2147483648 (java.lang.Integer.MIN_VALUE)
BIGINT
9223372036854775807 (java.lang.Long.MAX_VALUE)
-9223372036854775808 (java.lang.Long.MIN_VALUE)
Automatically generated values in an identity column are unique. Use a primary key or unique constraint on a column to guarantee uniqueness. Creating an identity column does not create an index on the column.
The IDENTITY_VAL_LOCAL function is a non-deterministic function that returns the most recently assigned value for an identity column. See IDENTITY_VAL_LOCAL function for more information.
Note: Specify the schema, table, and column name using the same case as those names are stored in the system tables--that is, all upper case unless you used delimited identifiers when creating those database objects.
Derby keeps track of the last increment value for a column in a cache. It also stores the value of what the next increment value will be for the column on disk in the AUTOINCREMENTVALUE column of the SYS.SYSCOLUMNS system table. Rolling back a transaction does not undo this value, and thus rolled-back transactions can leave "gaps" in the values automatically inserted into an identity column. Derby behaves this way to avoid locking a row in SYS.SYSCOLUMNS for the duration of a transaction and keeping concurrency high.
When an insert happens within a triggered-SQL-statement, the value inserted by the triggered-SQL-statement into the identity column is available from ConnectionInfo only within the trigger code. The trigger code is also able to see the value inserted by the statement that caused the trigger to fire. However, the statement that caused the trigger to fire is not able to see the value inserted by the triggered-SQL-statement into the identity column. Likewise, triggers can be nested (or recursive). An SQL statement can cause trigger T1 to fire. T1 in turn executes an SQL statement that causes trigger T2 to fire. If both T1 and T2 insert rows into a table that cause Derby to insert into an identity column, trigger T1 cannot see the value caused by T2's insert, but T2 can see the value caused by T1's insert. Each nesting level can see increment values generated by itself and previous nesting levels, all the way to the top-level SQL statement that initiated the recursive triggers. You can only have 16 levels of trigger recursion.
Example
create table greetings (i int generated by default as identity (START WITH 2, INCREMENT BY 1), ch char(50)); -- specify value "1": insert into greetings values (1, 'hi'); -- use generated default insert into greetings values (DEFAULT, 'salut'); -- use generated default insert into greetings(ch) values ('bonjour');
generation-clause:
GENERATED ALWAYS AS ( value-expression )
A value-expression is an Expression that resolves to a single value, with some limitations that are described here. See SQL expressions for more information about Expressions.
References
The generation-clause may reference other non-generated columns in the table, but it must not reference any generated column. The generation-clause must not reference a column in another table.
Functions
The generation-clause may invoke user-coded functions, if the functions meet the following requirements:
 
The functions must not read or write SQL data.
 
The functions must have been declared DETERMINISTIC.
 
The functions must not invoke any of the following possibly non-deterministic system functions:
 
CURRENT_DATE
 
CURRENT_TIME
 
CURRENT_TIMESTAMP
 
CURRENT_USER
 
CURRENT_ROLE
 
CURRENT SCHEMA
 
CURRENT SQLID
 
SESSION_USER
Subqueries
The generation-clause must not include subqueries.
Foreign keys
If the generated column is part of a foreign key that references another table, the referential action must not specify SET NULL or SET DEFAULT, and the update rule must not specify ON UPDATE CASCADE.
Example
CREATE TABLE employee ( employeeID int, name varchar( 50 ), caseInsensitiveName GENERATED ALWAYS AS( UPPER( name ) ) ); CREATE INDEX caseInsensitiveEmployeeName ON employee( caseInsensitiveName );
CREATE TRIGGER statement
A trigger defines a set of actions that are executed when a database event occurs on a specified table. A database event is a delete, insert, or update operation. For example, if you define a trigger for a delete on a particular table, the trigger's action occurs whenever someone deletes a row or rows from the table.
Along with constraints, triggers can help enforce data integrity rules with actions such as cascading deletes or updates. Triggers can also perform a variety of functions such as issuing alerts, updating other tables, sending e-mail, and other useful actions.
You can define any number of triggers for a single table, including multiple triggers on the same table for the same event.
You can create a trigger in any schema where you are the schema owner. To create a trigger on a table that you do not own, you must be granted the TRIGGER privilege on that table. The database owner can also create triggers on any table in any schema.
The trigger does not need to reside in the same schema as the table on which the trigger is defined.
If a qualified trigger name is specified, the schema name cannot begin with SYS.
Syntax
CREATE TRIGGER TriggerName { AFTER | NO CASCADE BEFORE } { INSERT | DELETE | UPDATE [ OF column-Name [, column-Name]* ] } ON table-Name [ ReferencingClause ] [ FOR EACH { ROW | STATEMENT } ] [ MODE DB2SQL ] Triggered-SQL-statement
Before or after: when triggers fire
Triggers are defined as either Before or After triggers.
 
Before triggers fire before the statement's changes are applied and before any constraints have been applied. Before triggers can be either row or statement triggers (see Statement versus row triggers).
 
After triggers fire after all constraints have been satisfied and after the changes have been applied to the target table. After triggers can be either row or statement triggers (see Statement versus row triggers).
Insert, delete, or update: what causes the trigger to fire
A trigger is fired by one of the following database events, depending on how you define it (see Syntax above):
 
INSERT
 
UPDATE
 
DELETE
You can define any number of triggers for a given event on a given table. For update, you can specify columns.
Referencing old and new values: the referencing clause
Many triggered-SQL-statements need to refer to data that is currently being changed by the database event that caused them to fire. The triggered-SQL-statement might need to refer to the new (post-change or "after") values.
Derby provides you with a number of ways to refer to data that is currently being changed by the database event that caused the trigger to fire. Changed data can be referred to in the triggered-SQL-statement using transition variables or transition tables. The referencing clause allows you to provide a correlation name or alias for these transition variables by specifying OLD/NEW AS correlation-Name .
For example, if you add the following clause to the trigger definition:
REFERENCING OLD AS DELETEDROW
you can then refer to this correlation name in the triggered-SQL-statement:
DELETE FROM HotelAvailability WHERE hotel_id = DELETEDROW.hotel_id
The OLD and NEW transition variables map to a java.sql.ResultSet with a single row.
Note: Only row triggers (see Statement versus row triggers) can use the transition variables. INSERT row triggers cannot reference an OLD row. DELETE row triggers cannot reference a NEW row.
For statement triggers, transition tables serve as a table identifier for the triggered-SQL-statement or the trigger qualification. The referencing clause allows you to provide a correlation name or alias for these transition tables by specifying OLD_TABLE/NEW_TABLE AS correlation-Name
For example:
REFERENCING OLD_TABLE AS DeletedHotels
allows you to use that new identifier (DeletedHotels) in the triggered-SQL-statement:
DELETE FROM HotelAvailability WHERE hotel_id IN (SELECT hotel_id FROM DeletedHotels)
The old and new transition tables map to a java.sql.ResultSet with cardinality equivalent to the number of rows affected by the triggering event.
Note: Only statement triggers (see Statement versus row triggers) can use the transition tables. INSERT statement triggers cannot reference an OLD table. DELETE statement triggers cannot reference a NEW table.
The referencing clause can designate only one new correlation or identifier and only one old correlation or identifier. Row triggers cannot designate an identifier for a transition table and statement triggers cannot designate a correlation for transition variables.
Statement versus row triggers
You have the option to specify whether a trigger is a statement trigger or a row trigger. If it is not specified in the CREATE TRIGGER statement via FOR EACH clause, then the trigger is a statement trigger by default.
 
statement triggers
A statement trigger fires once per triggering event and regardless of whether any rows are modified by the insert, update, or delete event.
 
row triggers
A row trigger fires once for each row affected by the triggering event. If no rows are affected, the trigger does not fire.
Note: An update that sets a column value to the value that it originally contained (for example, UPDATE T SET C = C) causes a row trigger to fire, even though the value of the column is the same as it was prior to the triggering event.
Triggered-SQL-statement
The action defined by the trigger is called the triggered-SQL-statement (in Syntax above, see the last line). It has the following limitations:
 
It must not contain any dynamic parameters (?).
 
It must not create, alter, or drop the table upon which the trigger is defined.
 
It must not add an index to or remove an index from the table on which the trigger is defined.
 
It must not add a trigger to or drop a trigger from the table upon which the trigger is defined.
 
It must not commit or roll back the current transaction or change the isolation level.
 
Before triggers cannot have INSERT, UPDATE or DELETE statements as their action.
 
Before triggers cannot call procedures that modify SQL data as their action.
 
The NEW variable of a Before trigger cannot reference a generated column.
The triggered-SQL-statement can reference database objects other than the table upon which the trigger is declared. If any of these database objects is dropped, the trigger is invalidated. If the trigger cannot be successfully recompiled upon the next execution, the invocation throws an exception and the statement that caused it to fire will be rolled back.
For more information on triggered-SQL-statements, see the Java DB Developer's Guide.
Order of execution
When a database event occurs that fires a trigger, Derby performs actions in this order:
 
It fires No Cascade Before triggers.
 
It performs constraint checking (primary key, unique key, foreign key, check).
 
It performs the insert, update, or delete.
 
It fires After triggers.
When multiple triggers are defined for the same database event for the same table for the same trigger time (before or after), triggers are fired in the order in which they were created.
-- Statements and triggers: CREATE TRIGGER t1 NO CASCADE BEFORE UPDATE ON x FOR EACH ROW MODE DB2SQL values app.notifyEmail('Jerry', 'Table x is about to be updated'); CREATE TRIGGER FLIGHTSDELETE AFTER DELETE ON FLIGHTS REFERENCING OLD_TABLE AS DELETEDFLIGHTS FOR EACH STATEMENT DELETE FROM FLIGHTAVAILABILITY WHERE FLIGHT_ID IN (SELECT FLIGHT_ID FROM DELETEDFLIGHTS); CREATE TRIGGER FLIGHTSDELETE3 AFTER DELETE ON FLIGHTS REFERENCING OLD AS OLD FOR EACH ROW DELETE FROM FLIGHTAVAILABILITY WHERE FLIGHT_ID = OLD.FLIGHT_ID;
Note: You can find more examples in the Java DB Developer's Guide.
Trigger recursion
The maximum trigger recursion depth is 16.
Related information
Special system functions that return information about the current time or current user are evaluated when the trigger fires, not when it is created. Such functions include:
ReferencingClause:
REFERENCING { { OLD | NEW } [ ROW ] [ AS ] correlation-Name [ { OLD | NEW } [ ROW ] [ AS ] correlation-Name ] | { OLD TABLE | NEW TABLE } [ AS ] Identifier [ { OLD TABLE | NEW TABLE } [AS] Identifier ] | { OLD_TABLE | NEW_TABLE } [ AS ] Identifier [ { OLD_TABLE | NEW_TABLE } [AS] Identifier ] }
Note: The OLD_TABLE | NEW_TABLE syntax is deprecated since it is not SQL compliant and is intended for backward compatibility and DB2 compatibility.
CREATE VIEW statement
Views are virtual tables formed by a query. A view is a dictionary object that you can use until you drop it. Views are not updatable.
If a qualified view name is specified, the schema name cannot begin with SYS.
The view owner automatically gains the SELECT privilege on the view. The SELECT privilege cannot be revoked from the view owner. The database owner automatically gains the SELECT privilege on the view and is able to grant this privilege to other users. The SELECT privilege cannot be revoked from the database owner.
The view owner can only grant the SELECT privilege to other users if the view owner also owns the underlying objects.
If the underlying objects that the view references are not owned by the view owner, the view owner must be granted the appropriate privileges. For example, if the authorization ID user2 attempts to create a view called user2.v2 that references table user1.t1 and function user1.f_abs(), then user2 must have the SELECT privilege on table user1.t1 and the EXECUTE privilege on function user1.f_abs().
The privilege to grant the SELECT privilege cannot be revoked. If a required privilege on one of the underlying objects that the view references is revoked, then the view is dropped.
Syntax
A view definition can contain an optional view column list to explicitly name the columns in the view. If there is no column list, the view inherits the column names from the underlying query. All columns in a view must be uniquely named.
CREATE VIEW SAMP.V1 (COL_SUM, COL_DIFF) AS SELECT COMM + BONUS, COMM - BONUS FROM SAMP.EMPLOYEE; CREATE VIEW SAMP.VEMP_RES (RESUME) AS VALUES 'Delores M. Quintana', 'Heather A. Nicholls', 'Bruce Adamson'; CREATE VIEW SAMP.PROJ_COMBO (PROJNO, PRENDATE, PRSTAFF, MAJPROJ) AS SELECT PROJNO, PRENDATE, PRSTAFF, MAJPROJ FROM SAMP.PROJECT UNION ALL SELECT PROJNO, EMSTDATE, EMPTIME, EMPNO FROM SAMP.EMP_ACT WHERE EMPNO IS NOT NULL;
Statement dependency system
View definitions are dependent on the tables and views referenced within the view definition. DML (data manipulation language) statements that contain view references depend on those views, as well as the objects in the view definitions that the views are dependent on. Statements that reference the view depend on indexes the view uses; which index a view uses can change from statement to statement based on how the query is optimized. For example, given:
CREATE TABLE T1 (C1 DOUBLE PRECISION); CREATE FUNCTION SIN (DATA DOUBLE) RETURNS DOUBLE EXTERNAL NAME 'java.lang.Math.sin' LANGUAGE JAVA PARAMETER STYLE JAVA; CREATE VIEW V1 (C1) AS SELECT SIN(C1) FROM T1;
the following SELECT:
SELECT * FROM V1
is dependent on view V1, table T1, and external scalar function SIN.
DECLARE GLOBAL TEMPORARY TABLE statement
The DECLARE GLOBAL TEMPORARY TABLE statement defines a temporary table for the current connection.
These tables do not reside in the system catalogs and are not persistent. Temporary tables exist only during the connection that declared them and cannot be referenced outside of that connection. When the connection closes, the rows of the table are deleted, and the in-memory description of the temporary table is dropped.
Temporary tables are useful when:
 
The table structure is not known before using an application.
 
Other users do not need the same table structure.
 
Data in the temporary table is needed while using the application.
 
The table can be declared and dropped without holding the locks on the system catalog.
Syntax
DECLARE GLOBAL TEMPORARY TABLE table-Name { column-definition [ , column-definition ] * } [ ON COMMIT {DELETE | PRESERVE} ROWS ] NOT LOGGED [ON ROLLBACK DELETE ROWS]
table-Name
Names the temporary table. If a schema-Name other than SESSION is specified, an error will occur (SQLSTATE 428EK). If the schema-Name is not specified, SESSION is assigned. Multiple connections can define declared global temporary tables with the same name because each connection has its own unique table descriptor for it.
Using SESSION as the schema name of a physical table will not cause an error, but is discouraged. The SESSION schema name should be reserved for the temporary table schema.
column-definition
See column-definition for CREATE TABLE for more information on column-definition. DECLARE GLOBAL TEMPORARY TABLE does not allow generated-column-spec in the column-definition.
Data type
Supported data types are:
 
BIGINT
 
CHAR
 
DATE
 
DECIMAL
 
DOUBLE
 
DOUBLE PRECISION
 
FLOAT
 
INTEGER
 
NUMERIC
 
REAL
 
SMALLINT
 
TIME
 
TIMESTAMP
 
VARCHAR
ON COMMIT
Specifies the action taken on the global temporary table when a COMMIT operation is performed.
DELETE ROWS
All rows of the table will be deleted if no hold-able cursor is open on the table. This is the default value for ON COMMIT. If you specify ON ROLLBACK DELETE ROWS, this will delete all the rows in the table only if the temporary table was used. ON COMMIT DELETE ROWS will delete the rows in the table even if the table was not used (if the table does not have hold-able cursors open on it).
PRESERVE ROWS
The rows of the table will be preserved.
NOT LOGGED
Specifies the action taken on the global temporary table when a rollback operation is performed. When a ROLLBACK (or ROLLBACK TO SAVEPOINT) operation is performed, if the table was created in the unit of work (or savepoint), the table will be dropped. If the table was dropped in the unit of work (or savepoint), the table will be restored with no rows.
ON ROLLBACK DELETE ROWS
This is the default value for NOT LOGGED. NOT LOGGED [ON ROLLBACK DELETE ROWS ]] specifies the action that is to be taken on the global temporary table when a ROLLBACK or (ROLLBACK TO SAVEPOINT) operation is performed. If the table data has been changed, all the rows will be deleted.
Examples
set schema myapp; create table t1(c11 int, c12 date); declare global temporary table SESSION.t1(c11 int) not logged; -- The SESSION qualification is redundant here because temporary -- tables can only exist in the SESSION schema. declare global temporary table t2(c21 int) not logged; -- The temporary table is not qualified here with SESSION because temporary -- tables can only exist in the SESSION schema. insert into SESSION.t1 values (1); -- SESSION qualification is mandatory here if you want to use -- the temporary table, because the current schema is "myapp." select * from t1; -- This select statement is referencing the "myapp.t1" physical -- table since the table was not qualified by SESSION.
Note: Temporary tables can be declared only in the SESSION schema. You should never declare a physical schema with the SESSION name.
The following is a list of DB2 UDB DECLARE GLOBAL TEMPORARY TABLE functions that are not supported by Derby:
 
IDENTITY column-options
 
IDENTITY attribute in copy-options
 
AS (fullselect) DEFINITION ONLY
 
NOT LOGGED ON ROLLBACK PRESERVE ROWS
 
IN tablespace-name
 
PARTITIONING KEY
 
WITH REPLACE
Restrictions on Declared Global Temporary Tables
Derby does not support the following features on temporary tables. Some of these features are specific to temporary tables and some are specific to Derby.
Temporary tables cannot be specified in the following statements:
 
ALTER TABLE
 
CREATE INDEX
 
CREATE SYNONYM
 
CREATE TRIGGER
 
CREATE VIEW
 
GRANT
 
LOCK TABLE
 
RENAME
 
REVOKE
You cannot use the following features with temporary tables:
 
Synonyms, triggers and views on SESSION schema tables (including physical tables and temporary tables)
 
Caching statements that reference SESSION schema tables and views
 
Temporary tables cannot be specified in referential constraints and primary keys
 
Temporary tables cannot be referenced in a triggered-SQL-statement
 
Check constraints on columns
 
Generated-column-spec
 
Importing into temporary tables
If a statement that performs an insert, update, or delete to the temporary table encounters an error, all the rows of the temporary table are deleted.
The following data types cannot be used with Declared Global Temporary Tables:
 
BLOB
 
CHAR FOR BIT DATA
 
CLOB
 
LONG VARCHAR
 
LONG VARCHAR FOR BIT DATA
 
VARCHAR FOR BIT DATA
 
XML
DELETE statement
Syntax
{ DELETE FROM table-Name [[AS] correlation-Name] [WHERE clause] | DELETE FROM table-Name WHERE CURRENT OF }
The first syntactical form, called a searched delete, removes all rows identified by the table name and WHERE clause.
The second syntactical form, called a positioned delete, deletes the current row of an open, updatable cursor. For more information about updatable cursors, see SELECT statement.
Examples
DELETE FROM SAMP.IN_TRAY stmt.executeUpdate("DELETE FROM SAMP.IN_TRAY WHERE CURRENT OF " + resultSet.getCursorName());
Statement dependency system
A searched delete statement depends on the table being updated, all of its conglomerates (units of storage such as heaps or indexes), and any other table named in the WHERE clause. A CREATE or DROP INDEX statement for the target table of a prepared searched delete statement invalidates the prepared searched delete statement.
The positioned delete statement depends on the cursor and any tables the cursor references. You can compile a positioned delete even if the cursor has not been opened yet. However, removing the open cursor with the JDBC close method invalidates the positioned delete.
A CREATE or DROP INDEX statement for the target table of a prepared positioned delete invalidates the prepared positioned delete statement.
DROP statements
Use DROP statements to remove functions, indexes, procedures, roles, schemas, synonyms, tables, triggers, and views.
DROP FUNCTION statement
Syntax
DROP FUNCTION function-name
Identifies the particular function to be dropped, and is valid only if there is exactly one function instance with the function-name in the schema. The identified function can have any number of parameters defined for it.
An error will occur in any of the following circumstances:
 
If no function with the indicated name exists in the named or implied schema (the error is SQLSTATE 42704)
 
If there is more than one specific instance of the function in the named or implied schema
 
If you try to drop a user-defined function that is invoked in the generation-clause of a generated column
 
If you try to drop a user-defined function that is invoked in a view
DROP INDEX statement
DROP INDEX removes the specified index.
Syntax
DROP INDEX index-Name
DROP INDEX OrigIndex DROP INDEX DestIndex
Statement dependency system
If there is an open cursor on the table from which the index is dropped, the DROP INDEX statement generates an error and does not drop the index. Otherwise, statements that depend on the index's table are invalidated.
DROP PROCEDURE statement
Syntax
DROP PROCEDURE procedure-Name
Identifies the particular procedure to be dropped, and is valid only if there is exactly one procedure instance with the procedure-name in the schema. The identified procedure can have any number of parameters defined for it. If no procedure with the indicated name in the named or implied schema, an error (SQLSTATE 42704) will occur. An error will also occur if there is more than one specific instance of the procedure in the named or implied schema.
DROP ROLE statement
The DROP ROLE statement allows you to drop an SQL role.
Only the database owner can drop a role.
For more information on roles, see "Using SQL roles" in the Java DB Developer's Guide.
Syntax
DROP ROLE roleName
Dropping a role has the effect of removing the role from the database dictionary. This means that no session user can henceforth set that role (see SET ROLE statement), and any existing sessions that have that role as the current role (see CURRENT_ROLE function) will now have a NULL CURRENT_ROLE. Dropping a role also has the effect of revoking that role from any user and role it has been granted to. See REVOKE statement for information on how revoking a role may impact any dependent objects.
Example
DROP ROLE reader;
DROP SCHEMA statement
The DROP SCHEMA statement drops a schema. The target schema must be empty for the drop to succeed.
Neither the APP schema (the default user schema) nor the SYS schema can be dropped.
Syntax
DROP SCHEMA schemaName RESTRICT
The RESTRICT keyword enforces the rule that no objects can be defined in the specified schema for the schema to be deleted from the database. The RESTRICT keyword is required
-- Drop the SAMP schema -- The SAMP schema may only be deleted from the database -- if no objects are defined in the SAMP schema. DROP SCHEMA SAMP RESTRICT
DROP SYNONYM statement
Drops the specified synonym from a table or view.
Syntax
DROP SYNONYM synonym-Name
DROP TABLE statement
DROP TABLE removes the specified table.
Syntax
DROP TABLE table-Name
Statement dependency system
Triggers, constraints (primary, unique, check and references from the table being dropped) and indexes on the table are silently dropped. The existence of an open cursor that references table being dropped cause the DROP TABLE statement to generate an error, and the table is not dropped.
Dropping a table invalidates statements that depend on the table. (Invalidating a statement causes it to be recompiled upon the next execution. See Interaction with the dependency system.)
DROP TRIGGER statement
DROP TRIGGER removes the specified trigger.
Syntax
DROP TRIGGER TriggerName
DROP TRIGGER TRIG1
Statement dependency system
When a table is dropped, all triggers on that table are automatically dropped. (You don't have to drop a table's triggers before dropping the table.)
DROP VIEW statement
Drops the specified view.
Syntax
DROP VIEW view-Name
DROP VIEW AnIdentifier
Statement dependency system
Any statements referencing the view are invalidated on a DROP VIEW statement. DROP VIEW is disallowed if there are any views or open cursors dependent on the view. The view must be dropped before any objects that it is dependent on can be dropped.
GRANT statement
Use the GRANT statement to give permissions to a specific user or role, or to all users, to perform actions on database objects. You can also use the GRANT statement to grant a role to a user, to PUBLIC, or to another role.
The following types of permissions can be granted:
 
Delete data from a specific table.
 
Insert data into a specific table.
 
Create a foreign key reference to the named table or to a subset of columns from a table.
 
Select data from a table, view, or a subset of columns in a table.
 
Create a trigger on a table.
 
Update data in a table or in a subset of columns in a table.
 
Run a specified function or procedure.
Before you issue a GRANT statement, check that the derby.database.sqlAuthorization property is set to true. The derby.database.sqlAuthorization property enables the SQL Authorization mode.
You can grant privileges to database objects that you are authorized to grant. See the CREATE statement for the database object that you want to grant privileges on for more information.
The syntax that you use for the GRANT statement depends on whether you are granting privileges to a table or to a routine, or granting a role.
For more information on using the GRANT statement, see "Using SQL standard authorization" in the Java DB Developer's Guide.
Syntax for tables
GRANT privilege-type ON [TABLE] { table-Name | view-Name } TO grantees
Syntax for routines
GRANT EXECUTE ON { FUNCTION | PROCEDURE } routine-designator TO grantees
Syntax for roles
GRANT roleName [ {, roleName }* ] TO grantees
Before you can grant a role to a user or to another role, you must create the role using the CREATE ROLE statement. Only the database owner can grant a role.
A role A contains another role B if role B is granted to role A, or is contained in a role C granted to role A. Privileges granted to a contained role are inherited by the containing roles. So the set of privileges identified by role A is the union of the privileges granted to role A and the privileges granted to any contained roles of role A.
privilege-types
ALL PRIVILEGES | privilege-list
privilege-list
table-privilege {, table-privilege }*
table-privilege
DELETE | INSERT | REFERENCES [column list] | SELECT [column list] | TRIGGER | UPDATE [column list]
column list
( column-identifier {, column-identifier}* )
Use the ALL PRIVILEGES privilege type to grant all of the permissions to the user or role for the specified table. You can also grant one or more table privileges by specifying a privilege-list.
Use the DELETE privilege type to grant permission to delete rows from the specified table.
Use the INSERT privilege type to grant permission to insert rows into the specified table.
Use the REFERENCES privilege type to grant permission to create a foreign key reference to the specified table. If a column list is specified with the REFERENCES privilege, the permission is valid on only the foreign key reference to the specified columns.
Use the SELECT privilege type to grant permission to perform SELECT statements on a table or view. If a column list is specified with the SELECT privilege, the permission is valid on only those columns. If no column list is specified, then the privilege is valid on all of the columns in the table.
Use the TRIGGER privilege type to grant permission to create a trigger on the specified table.
Use the UPDATE privilege type to grant permission to use the UPDATE statement on the specified table. If a column list is specified, the permission applies only to the specified columns. To update a row using a statement that includes a WHERE clause, you must have SELECT permission on the columns in the row that you want to update.
grantees
You can grant privileges or roles to specific users or roles or to all users. Use the keyword PUBLIC to specify all users. When PUBLIC is specified, the privileges or roles affect all current and future users. The privileges granted to PUBLIC and to individual users or roles are independent privileges. For example, a SELECT privilege on table t is granted to both PUBLIC and to the authorization ID harry. The SELECT privilege is later revoked from the authorization ID harry, but Harry can access the table t through the PUBLIC privilege.
Either the object owner or the database owner can grant privileges to a user or to a role. Only the database owner can grant a role to a user or to another role.
routine-designator
{ function-name | procedure-name }
Examples
To grant the SELECT privilege on table t to the authorization IDs maria and harry, use the following syntax:
GRANT SELECT ON TABLE t TO maria,harry
To grant the UPDATE and TRIGGER privileges on table t to the authorization IDs anita and zhi, use the following syntax:
GRANT UPDATE, TRIGGER ON TABLE t TO anita,zhi
To grant the SELECT privilege on table s.v to all users, use the following syntax:
GRANT SELECT ON TABLE s.v to PUBLIC
To grant the EXECUTE privilege on procedure p to the authorization ID george, use the following syntax:
GRANT EXECUTE ON PROCEDURE p TO george
To grant the role purchases_reader_role to the authorization IDs george and maria, use the following syntax:
GRANT purchases_reader_role TO george,maria
To grant the SELECT privilege on table t to the role purchases_reader_role, use the following syntax:
GRANT SELECT ON TABLE t TO purchases_reader_role
INSERT statement
An INSERT statement creates a row or rows and stores them in the named table. The number of values assigned in an INSERT statement must be the same as the number of specified or implied columns.
Whenever you insert into a table which has generated columns, Derby calculates the values of those columns.
Syntax
INSERT INTO table-Name [ (Simple-column-Name [ , Simple-column-Name]* ) ] Query
Query can be:
 
 
a VALUES list
 
a multiple-row VALUES expression
Single-row and multiple-row lists can include the keyword DEFAULT. Specifying DEFAULT for a column inserts the column's default value into the column. Another way to insert the default value into the column is to omit the column from the column list and only insert values into other columns in the table. For more information see VALUES Expression.
The DEFAULT literal is the only value which you can directly insert into a generated column.
 
UNION expressions
For more information about Query, see Query.
INSERT INTO COUNTRIES VALUES ('Taiwan', 'TW', 'Asia') -- Insert a new department into the DEPARTMENT table, -- but do not assign a manager to the new department INSERT INTO DEPARTMENT (DEPTNO, DEPTNAME, ADMRDEPT) VALUES ('E31', 'ARCHITECTURE', 'E01') -- Insert two new departments using one statement -- into the DEPARTMENT table as in the previous example, -- but do not assign a manager to the new department. INSERT INTO DEPARTMENT (DEPTNO, DEPTNAME, ADMRDEPT) VALUES ('B11', 'PURCHASING', 'B01'), ('E41', 'DATABASE ADMINISTRATION', 'E01') -- Create a temporary table MA_EMP_ACT with the -- same columns as the EMP_ACT table. -- Load MA_EMP_ACT with the rows from the EMP_ACT -- table with a project number (PROJNO) -- starting with the letters 'MA'. CREATE TABLE MA_EMP_ACT ( EMPNO CHAR(6) NOT NULL, PROJNO CHAR(6) NOT NULL, ACTNO SMALLINT NOT NULL, EMPTIME DEC(5,2), EMSTDATE DATE, EMENDATE DATE ); INSERT INTO MA_EMP_ACT SELECT * FROM EMP_ACT WHERE SUBSTR(PROJNO, 1, 2) = 'MA'; -- Insert the DEFAULT value for the LOCATION column INSERT INTO DEPARTMENT VALUES ('E31', 'ARCHITECTURE', '00390', 'E01', DEFAULT)
Statement dependency system
The INSERT statement depends on the table being inserted into, all of the conglomerates (units of storage such as heaps or indexes) for that table, and any other table named in the statement. Any statement that creates or drops an index or a constraint for the target table of a prepared INSERT statement invalidates the prepared INSERT statement.
LOCK TABLE statement
The LOCK TABLE statement allows you to explicitly acquire a shared or exclusive table lock on the specified table. The table lock lasts until the end of the current transaction.
To lock a table, you must either be the database owner or the table owner.
Explicitly locking a table is useful to:
 
Avoid the overhead of multiple row locks on a table (in other words, user-initiated lock escalation)
 
Avoid deadlocks
You cannot lock system tables with this statement.
Syntax
LOCK TABLE table-Name IN { SHARE | EXCLUSIVE } MODE
After a table is locked in either mode, a transaction does not acquire any subsequent row-level locks on a table. For example, if a transaction locks the entire Flights table in share mode in order to read data, a particular statement might need to lock a particular row in exclusive mode in order to update the row. However, the previous table-level lock on the Flights table forces the exclusive lock to be table-level as well.
If the specified lock cannot be acquired because another connection already holds a lock on the table, a statement-level exception is raised (SQLState X0X02) after the deadlock timeout period.
Examples
To lock the entire Flights table in share mode to avoid a large number of row locks, use the following statement:
LOCK TABLE Flights IN SHARE MODE; SELECT * FROM Flights WHERE orig_airport > 'OOO';
You have a transaction with multiple UPDATE statements. Since each of the individual statements acquires only a few row-level locks, the transaction will not automatically upgrade the locks to a table-level lock. However, collectively the UPDATE statements acquire and release a large number of locks, which might result in deadlocks. For this type of transaction, you can acquire an exclusive table-level lock at the beginning of the transaction. For example:
LOCK TABLE FlightAvailability IN EXCLUSIVE MODE; UPDATE FlightAvailability SET economy_seats_taken = (economy_seats_taken + 2) WHERE flight_id = 'AA1265' AND flight_date = DATE('2004-03-31'); UPDATE FlightAvailability SET economy_seats_taken = (economy_seats_taken + 2) WHERE flight_id = 'AA1265' AND flight_date = DATE('2004-04-11'); UPDATE FlightAvailability SET economy_seats_taken = (economy_seats_taken + 2) WHERE flight_id = 'AA1265' AND flight_date = DATE('2004-04-12'); UPDATE FlightAvailability SET economy_seats_taken = (economy_seats_taken + 2) WHERE flight_id = 'AA1265' AND flight_date = DATE('2004-04-15');
If a transaction needs to look at a table before updating the table, acquire an exclusive lock before selecting to avoid deadlocks. For example:
LOCK TABLE Maps IN EXCLUSIVE MODE; SELECT MAX(map_id) + 1 FROM Maps; -- INSERT INTO Maps . . .
RENAME statements
Use the Rename statements with indexes, columns, and tables.
RENAME COLUMN statement
Use the RENAME COLUMN statement to rename a column in a table.
The RENAME COLUMN statement allows you to rename an existing column in an existing table in any schema (except the schema SYS).
To rename a column, you must either be the database owner or the table owner.
Other types of table alterations are possible; see ALTER TABLE statement for more information.
Examples
To rename the manager column in table employee to supervisor, use the following syntax:
RENAME COLUMN EMPLOYEE.MANAGER TO SUPERVISOR
You can combine ALTER TABLE and RENAME COLUMN to modify a column's data type. To change column c1 of table t to the new data type NEWTYPE:
ALTER TABLE t ADD COLUMN c1_newtype NEWTYPE UPDATE t SET c1_newtype = c1 ALTER TABLE t DROP COLUMN c1 RENAME COLUMN t.c1_newtype TO c1
Usage notes
Restriction: If a view, trigger, check constraint, foreign key constraint, or generation-clause of a generated column references the column, an attempt to rename it will generate an error.
Restriction: The RENAME COLUMN statement is not allowed if there are any open cursors that reference the column that is being altered.
Note: If there is an index defined on the column, the column can still be renamed; the index is automatically updated to refer to the column by its new name
RENAME INDEX statement
This statement allows you to rename an index in the current schema. Users cannot rename indexes in the SYS schema.
Syntax
RENAME INDEX index-Name TO new-index-Name
RENAME INDEX DESTINDEX TO ARRIVALINDEX
Statement dependency system
RENAME INDEX is not allowed if there are any open cursors that reference the index being renamed.
RENAME TABLE statement
RENAME TABLE allows you to rename an existing table in any schema (except the schema SYS).
To rename a table, you must either be the database owner or the table owner.
Syntax
RENAME TABLE table-Name TO new-Table-Name
If there is a view or foreign key that references the table, attempts to rename it will generate an error. In addition, if there are any check constraints or triggers on the table, attempts to rename it will also generate an error.
RENAME TABLE SAMP.EMP_ACT TO EMPLOYEE_ACT
Also see ALTER TABLE statement for more information.
Statement dependency system
If there is an index defined on the table, the table can be renamed.
The RENAME TABLE statement is not allowed if there are any open cursors that reference the table that is being altered.
REVOKE statement
Use the REVOKE statement to remove permissions from a specific user or role, or from all users, to perform actions on database objects. You can also use the REVOKE statement to revoke a role from a user, from PUBLIC, or from another role.
The following types of permissions can be revoked:
 
Delete data from a specific table.
 
Insert data into a specific table.
 
Create a foreign key reference to the named table or to a subset of columns from a table.
 
Select data from a table, view, or a subset of columns in a table.
 
Create a trigger on a table.
 
Update data in a table or in a subset of columns in a table.
 
Run a specified routine (function or procedure).
The derby.database.sqlAuthorization property must be set to true before you can use the GRANT statement or the REVOKE statement. The derby.database.sqlAuthorization property enables SQL Authorization mode.
You can revoke privileges for an object if you are the owner of the object or the database owner.
The syntax that you use for the REVOKE statement depends on whether you are revoking privileges to a table or to a routine, or whether you are revoking a role.
For more information on using the REVOKE statement, see "Using SQL standard authorization" in the Java DB Developer's Guide.
Syntax for tables
REVOKE privilege-type ON [ TABLE ] { table-Name | view-Name } FROM grantees
Revoking a privilege without specifying a column list revokes the privilege for all of the columns in the table.
Syntax for routines
REVOKE EXECUTE ON { FUNCTION | PROCEDURE } routine-designator FROM grantees RESTRICT
You must use the RESTRICT clause on REVOKE statements for routines. The RESTRICT clause specifies that the EXECUTE privilege cannot be revoked if the specified routine is used in a view, trigger, or constraint, and the privilege is being revoked from the owner of the view, trigger, or constraint.
Syntax for roles
REVOKE roleName [ {, roleName }* ] FROM grantees
Only the database owner can revoke a role.
privilege-types
ALL PRIVILEGES | privilege-list
privilege-list
table-privilege {, table-privilege }*
table-privilege
DELETE | INSERT | REFERENCES [column list] | SELECT [column list] | TRIGGER | UPDATE [column list]
column list
( column-identifier {, column-identifier}* )
Use the ALL PRIVILEGES privilege type to revoke all of the permissions from the user or role for the specified table. You can also revoke one or more table privileges by specifying a privilege-list.
Use the DELETE privilege type to revoke permission to delete rows from the specified table.
Use the INSERT privilege type to revoke permission to insert rows into the specified table.
Use the REFERENCES privilege type to revoke permission to create a foreign key reference to the specified table. If a column list is specified with the REFERENCES privilege, the permission is revoked on only the foreign key reference to the specified columns.
Use the SELECT privilege type to revoke permission to perform SELECT statements on a table or view. If a column list is specified with the SELECT privilege, the permission is revoked on only those columns. If no column list is specified, then the privilege is valid on all of the columns in the table.
Use the TRIGGER privilege type to revoke permission to create a trigger on the specified table.
Use the UPDATE privilege type to revoke permission to use the UPDATE statement on the specified table. If a column list is specified, the permission is revoked only on the specified columns.
grantees
You can revoke the privileges from specific users or roles or from all users. Use the keyword PUBLIC to specify all users. The privileges revoked from PUBLIC and from individual users or roles are independent privileges. For example, a SELECT privilege on table t is granted to both PUBLIC and to the authorization ID harry. The SELECT privilege is later revoked from the authorization ID harry, but the authorization ID harry can access the table t through the PUBLIC privilege.
You can revoke a role from a role, from a user, or from PUBLIC.
Restriction: You cannot revoke the privileges of the owner of an object.
routine-designator
{ qualified-name [ signature ] }
Prepared statements and open result sets/cursors
Checking for privileges happens at statement execution time, so prepared statements are still usable after a revoke action. If sufficient privileges are still available for the session, prepared statements will be executed, and for queries, a result set will be returned.
Once a result set has been returned to the application (by executing a prepared statement or by direct execution), it will remain accessible even if privileges or roles are revoked in a way that would cause another execution of the same statement to fail.
Cascading object dependencies
For views, triggers, and constraints, if the privilege on which the object depends on is revoked, the object is automatically dropped. Derby does not try to determine if you have other privileges that can replace the privileges that are being revoked. For more information, see "SQL standard authorization" in the Java DB Developer's Guide.
Limitations
The following limitations apply to the REVOKE statement:
Table-level privileges
All of the table-level privilege types for a specified grantee and table ID are stored in one row in the SYSTABLEPERMS system table. For example, when user2 is granted the SELECT and DELETE privileges on table user1.t1, a row is added to the SYSTABLEPERMS table. The GRANTEE field contains user2 and the TABLEID contains user1.t1. The SELECTPRIV and DELETEPRIV fields are set to Y. The remaining privilege type fields are set to N.
When a grantee creates an object that relies on one of the privilege types, the Derby engine tracks the dependency of the object on the specific row in the SYSTABLEPERMS table. For example, user2 creates the view v1 by using the statement SELECT * FROM user1.t1, the dependency manager tracks the dependency of view v1 on the row in SYSTABLEPERMS for GRANTEE(user2), TABLEID(user1.t1). The dependency manager knows only that the view is dependent on a privilege type in that specific row, but does not track exactly which privilege type the view is dependent on.
When a REVOKE statement for a table-level privilege is issued for a grantee and table ID, all of the objects that are dependent on the grantee and table ID are dropped. For example, if user1 revokes the DELETE privilege on table t1 from user2, the row in SYSTABLEPERMS for GRANTEE(user2), TABLEID(user1.t1) is modified by the REVOKE statement. The dependency manager sends a revoke invalidation message to the view user2.v1 and the view is dropped even though the view is not dependent on the DELETE privilege for GRANTEE(user2), TABLEID(user1.t1).
Column-level privileges
Only one type of privilege for a specified grantee and table ID are stored in one row in the SYSCOLPERMS system table. For example, when user2 is granted the SELECT privilege on table user1.t1 for columns c12 and c13, a row is added to the SYSCOLPERMS. The GRANTEE field contains user2, the TABLEID contains user1.t1, the TYPE field contains S, and the COLUMNS field contains c12, c13.
When a grantee creates an object that relies on the privilege type and the subset of columns in a table ID, the Derby engine tracks the dependency of the object on the specific row in the SYSCOLPERMS table. For example, user2 creates the view v1 by using the statement SELECT c11 FROM user1.t1, the dependency manager tracks the dependency of view v1 on the row in SYSCOLPERMS for GRANTEE(user2), TABLEID(user1.t1), TYPE(S). The dependency manager knows that the view is dependent on the SELECT privilege type, but does not track exactly which columns the view is dependent on.
When a REVOKE statement for a column-level privilege is issued for a grantee, table ID, and type, all of the objects that are dependent on the grantee, table ID, and type are dropped. For example, if user1 revokes the SELECT privilege on column c12 on table user1.t1 from user2, the row in SYSCOLPERMS for GRANTEE(user2), TABLEID(user1.t1), TYPE(S) is modified by the REVOKE statement. The dependency manager sends a revoke invalidation message to the view user2.v1 and the view is dropped even though the view is not dependent on the column c12 for GRANTEE(user2), TABLEID(user1.t1), TYPE(S).
Roles
Derby tracks any dependencies on the definer's current role for views, constraints, and triggers. If privileges were obtainable only via the current role when the object in question was defined, that object depends on the current role. The object will be dropped if the role is revoked from the defining user or from PUBLIC, as the case may be. Also, if a contained role of the current role in such cases is revoked, dependent objects will be dropped. Note that dropping may be too pessimistic. This is because Derby does not currently make an attempt to recheck if the necessary privileges are still available in such cases.
Revoke examples
To revoke the SELECT privilege on table t from the authorization IDs maria and harry, use the following syntax:
REVOKE SELECT ON TABLE t FROM maria,harry
To revoke the UPDATE and TRIGGER privileges on table t from the authorization IDs anita and zhi, use the following syntax:
REVOKE UPDATE, TRIGGER ON TABLE t FROM anita,zhi
To revoke the SELECT privilege on table s.v from all users, use the following syntax:
REVOKE SELECT ON TABLE s.v FROM PUBLIC
To revoke the UPDATE privilege on columns c1 and c2 of table s.v from all users, use the following syntax:
REVOKE UPDATE (c1,c2) ON TABLE s.v FROM PUBLIC
To revoke the EXECUTE privilege on procedure p from the authorization ID george, use the following syntax:
REVOKE EXECUTE ON PROCEDURE p FROM george RESTRICT
To revoke the role purchases_reader_role from the authorization IDs george and maria, use the following syntax:
REVOKE purchases_reader_role FROM george,maria
To revoke the SELECT privilege on table t from the role purchases_reader_role, use the following syntax:
REVOKE SELECT ON TABLE t FROM purchases_reader_role
SET statements
Use the SET statements to set the current role, schema, or isolation level.
SET ISOLATION statement
The SET ISOLATION statement allows a user to change the isolation level for the user's connection. Valid levels are SERIALIZABLE, REPEATABLE READ, READ COMMITTED, and READ UNCOMMITTED.
Issuing this statement always commits the current transaction. The JDBC java.sql.Connection.setTransactionIsolation method behaves almost identically to this command, with one exception: if you are using the embedded driver, and if the call to java.sql.Connection.setTransactionIsolation does not actually change the isolation level (that is, if it sets the isolation level to its current value), the current transaction is not committed.
For information about isolation levels, see "Locking, concurrency, and isolation" in the Java DB Developer's Guide. For information about the JDBC java.sql.Connection.setTransactionIsolation method, see java.sql.Connection.setTransactionIsolation method.
Syntax
SET [ CURRENT ] ISOLATION [ = ] { UR | DIRTY READ | READ UNCOMMITTED CS | READ COMMITTED | CURSOR STABILITY RS | RR | REPEATABLE READ | SERIALIZABLE RESET }
set isolation serializable;
SET ROLE statement
The SET ROLE statement allows you to set the current role for the current SQL context of a session.
You can set a role only if the current user has been granted the role, or if the role has been granted to PUBLIC.
For more information on roles, see "Using SQL roles" in the Java DB Developer's Guide.
Syntax
SET ROLE { roleName | 'string-constant' | ? | NONE }
If you specify a roleName of NONE, the effect is to unset the current role.
If you specify the role as a string constant or as a dynamic parameter specification (?), any leading and trailing blanks are trimmed from the string before attempting to use the remaining (sub)string as a roleName. The dynamic parameter specification can be used in prepared statements, so the SET ROLE statement can be prepared once and then executed with different role values. You cannot specify NONE as a dynamic parameter.
Setting a role identifies a set of privileges that is a union of the following:
 
The privileges granted to that role
 
The union of privileges of roles contained in that role (for a definition of role containment, see "Syntax for roles" in GRANT statement)
In a session, the current privileges define what the session is allowed to access. The current privileges are the union of the following:
 
The privileges granted to the current user
 
The privileges granted to PUBLIC
 
The privileges identified by the current role, if set
The SET ROLE statement is not transactional; a rollback does not undo the effect of setting a role. If a transaction is in progress, an attempt to set a role results in an error.
Examples
SET ROLE reader;
// These examples show the use of SET ROLE in JDBC statements. // The case normal form is visible in the SYS.SYSROLES system table. stmt.execute("SET ROLE admin"); -- case normal form: ADMIN stmt.execute("SET ROLE \"admin\""); -- case normal form: admin stmt.execute("SET ROLE none"); -- special case PreparedStatement ps = conn.prepareStatement("SET ROLE ?"); ps.setString(1, " admin "); -- on execute: case normal form: ADMIN ps.setString(1, "\"admin\""); -- on execute: case normal form: admin ps.setString(1, "none"); -- on execute: syntax error ps.setString(1, "\"none\""); -- on execute: case normal form: none
SET SCHEMA statement
The SET SCHEMA statement sets the default schema for a connection's session to the designated schema. The default schema is used as the target schema for all statements issued from the connection that do not explicitly specify a schema name.
The target schema must exist for the SET SCHEMA statement to succeed. If the schema doesn't exist an error is returned. See CREATE SCHEMA statement.
The SET SCHEMA statement is not transactional: If the SET SCHEMA statement is part of a transaction that is rolled back, the schema change remains in effect.
Syntax
SET [CURRENT] SCHEMA [=] { schemaName| USER | ? | '<string-constant>' } | SET CURRENT SQLID [=] { schemaName| USER | ? | '<string-constant>' }
schemaName is an identifier with a maximum length of 128. It is case insensitive unless enclosed in double quotes. (For example, SYS is equivalent to sYs, SYs, sys, etcetera.)
USER is the current user. If no current user is defined, the current schema defaults the APP schema. (If a user name was specified upon connection, the user's name is the default schema for the connection, if a schema with that name exists.)
? is a dynamic parameter specification that can be used in prepared statements. The SET SCHEMA statement can be prepared once and then executed with different schema values. The schema values are treated as string constants so they are case sensitive. For example, to designate the APP schema, use the string "APP" rather than "app".
-- the following are all equivalent and will work -- assuming a schema called HOTEL SET SCHEMA HOTEL SET SCHEMA hotel SET CURRENT SCHEMA hotel SET CURRENT SQLID hotel SET SCHEMA = hotel SET CURRENT SCHEMA = hotel SET CURRENT SQLID = hotel SET SCHEMA "HOTEL" -- quoted identifier SET SCHEMA 'HOTEL' -- quoted string--This example produces an error because --lower case hotel won't be found SET SCHEMA = 'hotel' --This example produces an error because SQLID is not --allowed without CURRENT SET SQLID hotel -- This sets the schema to the current user id SET CURRENT SCHEMA USER // Here's an example of using set schema in an Java program PreparedStatement ps = conn.PrepareStatement("set schema ?"); ps.setString(1,"HOTEL"); ps.executeUpdate(); ... do some work ps.setString(1,"APP"); ps.executeUpdate(); ps.setString(1,"app"); //error - string is case sensitive // no app will be found ps.setNull(1, Types.VARCHAR); //error - null is not allowed
SELECT statement
A SELECT statement consists of a query with an optional ORDER BY clause, an optional result offset clause, an optional fetch first clause, an optional FOR UPDATE clause and optionally isolation level. The SELECT statement is so named because the typical first word of the query construct is SELECT. (Query includes the VALUES expression and UNION, INTERSECT, and EXCEPT expressions as well as SELECT expressions).
The ORDER BY clause guarantees the ordering of the ResultSet. The result offset clause and the fetch first clause can be used to fetch only a subset of the otherwise selected rows, possibly with an offset into the result set. The FOR UPDATE clause makes the result set's cursor updatable. The SELECT statement supports the FOR FETCH ONLY clause. The FOR FETCH ONLY clause is synonymous with the FOR READ ONLY clause.
You can set the isolation level in a SELECT statement using the WITH {RR|RS|CS|UR} syntax.
Example
-- lists the names of the expression -- SAL+BONUS+COMM as TOTAL_PAY and -- orders by the new name TOTAL_PAY SELECT FIRSTNME, SALARY+BONUS+COMM AS TOTAL_PAY FROM EMPLOYEE ORDER BY TOTAL_PAY -- creating an updatable cursor with a FOR UPDATE clause -- to update the start date (PRSTDATE) and the end date (PRENDATE) -- columns in the PROJECT table SELECT PROJNO, PRSTDATE, PRENDATE FROM PROJECT FOR UPDATE OF PRSTDATE, PRENDATE -- set the isolation level to RR for this statement only SELECT * FROM Flights WHERE flight_id BETWEEN 'AA1111' AND 'AA1112' WITH RR
A SELECT statement returns a ResultSet. A cursor is a pointer to a specific row in ResultSet. In Java applications, all ResultSets have an underlying associated SQL cursor, often referred to as the result set's cursor. The cursor can be updatable, that is, you can update or delete rows as you step through the ResultSet if the SELECT statement that generated it and its underlying query meet cursor updatability requirements, as detailed below. The FOR UPDATE clause can be used to ensure a compilation check that the SELECT statement meets the requiremments of a updatable cursors, or to limit the columns that can be updated.
Note: The ORDER BY clause allows you to order the results of the SELECT. Without the ORDER BY clause, the results are returned in random order.
Requirements for updatable cursors and updatable ResultSets
Only simple, single-table SELECT cursors can be updatable. The SELECT statement for updatable ResultSets has the same syntax as the SELECT statement for updatable cursors. To generate updatable cursors:
 
The SELECT statement must not include an ORDER BY clause.
 
The underlying Query must be a SelectExpression.
 
The SelectExpression in the underlying Query must not include:
 
DISTINCT
 
Aggregates
 
GROUP BY clause
 
HAVING clause
 
ORDER BY clause
 
The FROM clause in the underlying Query must not have:
 
more than one table in its FROM clause
 
anything other than one table name
 
 
subqueries
 
If the underlying Query has a WHERE clause, the WHERE clause must not have subqueries.
Note: Cursors are read-only by default. To produce an updatable cursor besides meeting the requirements listed above, the concurrency mode for the ResultSet must be ResultSet.CONCUR_UPDATABLE or the SELECT statement must have FOR UPDATE in the FOR clause (see FOR UPDATE clause).
There is no SQL language statement to assign a name to a cursor. Instead, one can use the JDBC API to assign names to cursors or retrieve system-generated names. For more information, see Naming or accessing the name of a cursor in the Java DB Developer's Guide.
Statement dependency system
The SELECT depends on all the tables and views named in the query and the conglomerates (units of storage such as heaps and indexes) chosen for access paths on those tables. CREATE INDEX does not invalidate a prepared SELECT statement. A DROP INDEX statement invalidates a prepared SELECT statement if the index is an access path in the statement. If the SELECT includes views, it also depends on the dictionary objects on which the view itself depends (see CREATE VIEW statement).
Any prepared UPDATE WHERE CURRENT or DELETE WHERE CURRENT statement against a cursor of a SELECT depends on the SELECT. Removing a SELECT through a java.sql.Statement.close request invalidates the UPDATE WHERE CURRENT or DELETE WHERE CURRENT.
The SELECT depends on all aliases used in the query. Dropping an alias invalidates a prepared SELECT statement if the statement uses the alias.
UPDATE statement
Syntax
{ UPDATE table-Name [[AS] correlation-Name] SET column-Name = Value [ , column-Name = Value} ]* [WHERE clause] | UPDATE table-Name SET column-Name = Value [ , column-Name = Value ]* WHERE CURRENT OF }
where Value is defined as follows:
Expression | DEFAULT
The first syntactical form, called a searched update, updates the value of one or more columns for all rows of the table for which the WHERE clause evaluates to TRUE.
The second syntactical form, called a positioned update, updates one or more columns on the current row of an open, updatable cursor. If columns were specified in the FOR UPDATE clause of the SELECT statement used to generate the cursor, only those columns can be updated. If no columns were specified or the select statement did not include a FOR UPDATE clause, all columns may be updated.
Specifying DEFAULT for the update value sets the value of the column to the default defined for that table.
The DEFAULT literal is the only value which you can directly assign to a generated column. Whenever you alter the value of a column referenced by the generation-clause of a generated column, Derby recalculates the value of the generated column.
Example
-- All the employees except the manager of -- department (WORKDEPT) 'E21' have been temporarily reassigned. -- Indicate this by changing their job (JOB) to NULL and their pay -- (SALARY, BONUS, COMM) values to zero in the EMPLOYEE table. UPDATE EMPLOYEE SET JOB=NULL, SALARY=0, BONUS=0, COMM=0 WHERE WORKDEPT = 'E21' AND JOB <> 'MANAGER' -- PROMOTE the job (JOB) of employees without a specific job title to MANAGER UPDATE EMPLOYEE SET JOB = 'MANAGER' WHERE JOB IS NULL; // Increase the project staffing (PRSTAFF) by 1.5 for all projects stmt.executeUpdate("UPDATE PROJECT SET PRSTAFF = " "PRSTAFF + 1.5" + "WHERE CURRENT OF" + ResultSet.getCursorName()); -- Change the job (JOB) of employee number (EMPNO) '000290' in the EMPLOYEE table -- to its DEFAULT value which is NULL UPDATE EMPLOYEE SET JOB = DEFAULT WHERE EMPNO = '000290'
Statement dependency system
A searched update statement depends on the table being updated, all of its conglomerates (units of storage such as heaps or indexes), all of its constraints, and any other table named in the WHERE clause or SET expressions. A CREATE or DROP INDEX statement or an ALTER TABLE statement for the target table of a prepared searched update statement invalidates the prepared searched update statement.
The positioned update statement depends on the cursor and any tables the cursor references. You can compile a positioned update even if the cursor has not been opened yet. However, removing the open cursor with the JDBC close method invalidates the positioned update.
A CREATE or DROP INDEX statement or an ALTER TABLE statement for the target table of a prepared positioned update invalidates the prepared positioned update statement.
Dropping an alias invalidates a prepared update statement if the latter statement uses the alias.
Dropping or adding triggers on the target table of the update invalidates the update statement.
SQL clauses
CONSTRAINT clause
A CONSTRAINT clause is an optional part of a CREATE TABLE statement or ALTER TABLE statement. A constraint is a rule to which data must conform. Constraint names are optional.
A CONSTRAINT can be one of the following:
 
a column-level constraint
Column-level constraints refer to a single column in the table and do not specify a column name (except check constraints). They refer to the column that they follow.
 
a table-level constraint
Table-level constraints refer to one or more columns in the table. Table-level constraints specify the names of the columns to which they apply. Table-level CHECK constraints can refer to 0 or more columns in the table.
Column constraints include:
 
NOT NULL
Specifies that this column cannot hold NULL values (constraints of this type are not nameable).
 
PRIMARY KEY
Specifies the column that uniquely identifies a row in the table. The identified columns must be defined as NOT NULL.
Note: If you attempt to add a primary key using ALTER TABLE and any of the columns included in the primary key contain null values, an error will be generated and the primary key will not be added. See ALTER TABLE statement for more information.
 
UNIQUE
Specifies that values in the column must be unique.
 
FOREIGN KEY
Specifies that the values in the column must correspond to values in a referenced primary key or unique key column or that they are NULL.
 
CHECK
Specifies rules for values in the column.
Table constraints include:
 
PRIMARY KEY
Specifies the column or columns that uniquely identify a row in the table. NULL values are not allowed.
 
UNIQUE
Specifies that values in the columns must be unique.
 
FOREIGN KEY
Specifies that the values in the columns must correspond to values in referenced primary key or unique columns or that they are NULL.
Note: If the foreign key consists of multiple columns, and any column is NULL, the whole key is considered NULL. The insert is permitted no matter what is on the non-null columns.
 
CHECK
Specifies a wide range of rules for values in the table.
Column constraints and table constraints have the same function; the difference is in where you specify them. Table constraints allow you to specify more than one column in a PRIMARY KEY, UNIQUE, CHECK, or FOREIGN KEY constraint definition. Column-level constraints (except for check constraints) refer to only one column.
Syntax
Primary key constraints
A primary key defines the set of columns that uniquely identifies rows in a table.
When you create a primary key constraint, none of the columns included in the primary key can have NULL constraints; that is, they must not permit NULL values.
ALTER TABLE ADD PRIMARY KEY allows you to include existing columns in a primary key if they were first defined as NOT NULL. NULL values are not allowed. If the column(s) contain NULL values, the system will not add the primary key constraint. See ALTER TABLE statement for more information.
A table can have at most one PRIMARY KEY constraint.
Unique constraints
A UNIQUE constraint defines a set of columns that uniquely identify rows in a table only if all the key values are not NULL. If one or more key parts are NULL, duplicate keys are allowed.
For example, if there is a UNIQUE constraint on col1 and col2 of a table, the combination of the values held by col1 and col2 will be unique as long as these values are not NULL. If one of col1 and col2 holds a NULL value, there can be another identical row in the table.
A table can have multiple UNIQUE constraints.
Foreign key constraints
Foreign keys provide a way to enforce the referential integrity of a database. A foreign key is a column or group of columns within a table that references a key in some other table (or sometimes, though rarely, the same table). The foreign key must always include the columns of which the types exactly match those in the referenced primary key or unique constraint.
For a table-level foreign key constraint in which you specify the columns in the table that make up the constraint, you cannot use the same column more than once.
If there is a column list in the ReferencesSpecification (a list of columns in the referenced table), it must correspond either to a unique constraint or to a primary key constraint in the referenced table. The ReferencesSpecification can omit the column list for the referenced table if that table has a declared primary key.
If there is no column list in the ReferencesSpecification and the referenced table has no primary key, a statement exception is thrown. (This means that if the referenced table has only unique keys, you must include a column list in the ReferencesSpecification.)
A foreign key constraint is satisfied if there is a matching value in the referenced unique or primary key column. If the foreign key consists of multiple columns, the foreign key value is considered NULL if any of its columns contains a NULL.
Note: It is possible for a foreign key consisting of multiple columns to allow one of the columns to contain a value for which there is no matching value in the referenced columns, per the SQL-92 standard. To avoid this situation, create NOT NULL constraints on all of the foreign key's columns.
Foreign key constraints and DML
When you insert into or update a table with an enabled foreign key constraint, Derby checks that the row does not violate the foreign key constraint by looking up the corresponding referenced key in the referenced table. If the constraint is not satisfied, Derby rejects the insert or update with a statement exception.
When you update or delete a row in a table with a referenced key (a primary or unique constraint referenced by a foreign key), Derby checks every foreign key constraint that references the key to make sure that the removal or modification of the row does not cause a constraint violation. If removal or modification of the row would cause a constraint violation, the update or delete is not permitted and Derby throws a statement exception.
Derby performs constraint checks at the time the statement is executed, not when the transaction commits.
Backing indexes
UNIQUE, PRIMARY KEY, and FOREIGN KEY constraints generate indexes that enforce or "back" the constraint (and are sometimes called backing indexes). PRIMARY KEY constraints generate unique indexes. FOREIGN KEY constraints generate non-unique indexes. UNIQUE constraints generate unique indexes if all the columns are non-nullable, and they generate non-unique indexes if one or more columns are nullable. Therefore, if a column or set of columns has a UNIQUE, PRIMARY KEY, or FOREIGN KEY constraint on it, you do not need to create an index on those columns for performance. Derby has already created it for you. See Indexes and constraints.
These indexes are available to the optimizer for query optimization (see CREATE INDEX statement) and have system-generated names.
You cannot drop backing indexes with a DROP INDEX statement; you must drop the constraint or the table.
Check constraints
A check constraint can be used to specify a wide range of rules for the contents of a table. A search condition (which is a boolean expression) is specified for a check constraint. This search condition must be satisfied for all rows in the table. The search condition is applied to each row that is modified on an INSERT or UPDATE at the time of the row modification. The entire statement is aborted if any check constraint is violated.
Requirements for search condition
If a check constraint is specified as part of a column-definition, a column reference can only be made to the same column. Check constraints specified as part of a table definition can have column references identifying columns previously defined in the CREATE TABLE statement.
The search condition must always return the same value if applied to the same values. Thus, it cannot contain any of the following:
 
Dynamic parameters (?)
 
Date/Time Functions (CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP)
 
Subqueries
 
User Functions (such as USER, SESSION_USER, CURRENT_USER)
Referential actions
You can specify an ON DELETE clause and/or an ON UPDATE clause, followed by the appropriate action (CASCADE, RESTRICT, SET NULL, or NO ACTION) when defining foreign keys. These clauses specify whether Derby should modify corresponding foreign key values or disallow the operation, to keep foreign key relationships intact when a primary key value is updated or deleted from a table.
You specify the update and delete rule of a referential constraint when you define the referential constraint.
The update rule applies when a row of either the parent or dependent table is updated. The choices are NO ACTION and RESTRICT.
When a value in a column of the parent table's primary key is updated and the update rule has been specified as RESTRICT, Derby checks dependent tables for foreign key constraints. If any row in a dependent table violates a foreign key constraint, the transaction is rolled back.
If the update rule is NO ACTION, Derby checks the dependent tables for foreign key constraints after all updates have been executed but before triggers have been executed. If any row in a dependent table violates a foreign key constraint, the statement is rejected.
When a value in a column of the dependent table is updated, and that value is part of a foreign key, NO ACTION is the implicit update rule. NO ACTION means that if a foreign key is updated with a non-null value, the update value must match a value in the parent table's primary key when the update statement is completed. If the update does not match a value in the parent table's primary key, the statement is rejected.
The delete rule applies when a row of the parent table is deleted and that row has dependents in the dependent table of the referential constraint. If rows of the dependent table are deleted, the delete operation on the parent table is said to be propagated to the dependent table. If the dependent table is also a parent table, the action specified applies, in turn, to its dependents.
The choices are NO ACTION, RESTRICT, CASCADE, or SET NULL. SET NULL can be specified only if some column of the foreign key allows null values.
If the delete rule is:
NO ACTION, Derby checks the dependent tables for foreign key constraints after all deletes have been executed but before triggers have been executed. If any row in a dependent table violates a foreign key constraint, the statement is rejected.
RESTRICT, Derby checks dependent tables for foreign key constraints. If any row in a dependent table violates a foreign key constraint, the transaction is rolled back.
CASCADE, the delete operation is propagated to the dependent table (and that table's dependents, if applicable).
SET NULL, each nullable column of the dependent table's foreign key is set to null. (Again, if the dependent table also has dependent tables, nullable columns in those tables' foreign keys are also set to null.)
Each referential constraint in which a table is a parent has its own delete rule; all applicable delete rules are used to determine the result of a delete operation. Thus, a row cannot be deleted if it has dependents in a referential constraint with a delete rule of RESTRICT or NO ACTION. Similarly, a row cannot be deleted if the deletion cascades to any of its descendants that are dependents in a referential constraint with the delete rule of RESTRICT or NO ACTION.
Deleting a row from the parent table involves other tables. Any table involved in a delete operation on the parent table is said to be delete-connected to the parent table. The delete can affect rows of these tables in the following ways:
 
If the delete rule is RESTRICT or NO ACTION, a dependent table is involved in the operation but is not affected by the operation. (That is, Derby checks the values within the table, but does not delete any values.)
 
If the delete rule is SET NULL, a dependent table's rows can be updated when a row of the parent table is the object of a delete or propagated delete operation.
 
If the delete rule is CASCADE, a dependent table's rows can be deleted when a parent table is the object of a delete.
 
If the dependent table is also a parent table, the actions described in this list apply, in turn, to its dependents.
Examples
-- column-level primary key constraint named OUT_TRAY_PK: CREATE TABLE SAMP.OUT_TRAY ( SENT TIMESTAMP, DESTINATION CHAR(8), SUBJECT CHAR(64) NOT NULL CONSTRAINT OUT_TRAY_PK PRIMARY KEY, NOTE_TEXT VARCHAR(3000) ); -- the table-level primary key definition allows you to -- include two columns in the primary key definition: CREATE TABLE SAMP.SCHED ( CLASS_CODE CHAR(7) NOT NULL, DAY SMALLINT NOT NULL, STARTING TIME, ENDING TIME, PRIMARY KEY (CLASS_CODE, DAY) ); -- Use a column-level constraint for an arithmetic check -- Use a table-level constraint -- to make sure that a employee's taxes does not -- exceed the bonus CREATE TABLE SAMP.EMP ( EMPNO CHAR(6) NOT NULL CONSTRAINT EMP_PK PRIMARY KEY, FIRSTNME CHAR(12) NOT NULL, MIDINIT vARCHAR(12) NOT NULL, LASTNAME VARCHAR(15) NOT NULL, SALARY DECIMAL(9,2) CONSTRAINT SAL_CK CHECK (SALARY >= 10000), BONUS DECIMAL(9,2), TAX DECIMAL(9,2), CONSTRAINT BONUS_CK CHECK (BONUS > TAX) ); -- use a check constraint to allow only appropriate -- abbreviations for the meals CREATE TABLE FLIGHTS ( FLIGHT_ID CHAR(6) NOT NULL , SEGMENT_NUMBER INTEGER NOT NULL , ORIG_AIRPORT CHAR(3), DEPART_TIME TIME, DEST_AIRPORT CHAR(3), ARRIVE_TIME TIME, MEAL CHAR(1) CONSTRAINT MEAL_CONSTRAINT CHECK (MEAL IN ('B', 'L', 'D', 'S')), PRIMARY KEY (FLIGHT_ID, SEGMENT_NUMBER) ); CREATE TABLE METROPOLITAN ( HOTEL_ID INT NOT NULL CONSTRAINT HOTELS_PK PRIMARY KEY, HOTEL_NAME VARCHAR(40) NOT NULL, CITY_ID INT CONSTRAINT METRO_FK REFERENCES CITIES ); -- create a table with a table-level primary key constraint -- and a table-level foreign key constraint CREATE TABLE FLTAVAIL ( FLIGHT_ID CHAR(6) NOT NULL, SEGMENT_NUMBER INT NOT NULL, FLIGHT_DATE DATE NOT NULL, ECONOMY_SEATS_TAKEN INT, BUSINESS_SEATS_TAKEN INT, FIRSTCLASS_SEATS_TAKEN INT, CONSTRAINT FLTAVAIL_PK PRIMARY KEY (FLIGHT_ID, SEGMENT_NUMBER), CONSTRAINT FLTS_FK FOREIGN KEY (FLIGHT_ID, SEGMENT_NUMBER) REFERENCES Flights (FLIGHT_ID, SEGMENT_NUMBER) ); -- add a unique constraint to a column ALTER TABLE SAMP.PROJECT ADD CONSTRAINT P_UC UNIQUE (PROJNAME); -- create a table whose city_id column references the -- primary key in the Cities table -- using a column-level foreign key constraint CREATE TABLE CONDOS ( CONDO_ID INT NOT NULL CONSTRAINT hotels_PK PRIMARY KEY, CONDO_NAME VARCHAR(40) NOT NULL, CITY_ID INT CONSTRAINT city_foreign_key REFERENCES Cities ON DELETE CASCADE ON UPDATE RESTRICT );
Statement dependency system
INSERT and UPDATE statements depend on all constraints on the target table. DELETEs depend on unique, primary key, and foreign key constraints. These statements are invalidated if a constraint is added to or dropped from the target table.
Column-level-constraint
{ NOT NULL | [ [CONSTRAINT constraint-Name] { CHECK (searchCondition) | { PRIMARY KEY | UNIQUE | REFERENCES clause } } }
Table-level constraint
[CONSTRAINT constraint-Name] { CHECK (searchCondition) | { PRIMARY KEY ( Simple-column-Name [ , Simple-column-Name ]* ) | UNIQUE ( Simple-column-Name [ , Simple-column-Name ]* ) | FOREIGN KEY ( Simple-column-Name [ , Simple-column-Name ]* ) REFERENCES clause } }
References specification
REFERENCES table-Name [ ( Simple-column-Name [ , Simple-column-Name ]* ) ] [ ON DELETE {NO ACTION | RESTRICT | CASCADE | SET NULL}] [ ON UPDATE {NO ACTION | RESTRICT }] | [ ON UPDATE {NO ACTION | RESTRICT }] [ ON DELETE {NO ACTION | RESTRICT | CASCADE | SET NULL}]
searchCondition
A searchCondition is any Boolean expression that meets the requirements specified in Requirements for search condition.
If a constraint-Name is not specified, Derby generates a unique constraint name (for either column or table constraints).
FOR UPDATE clause
The FOR UPDATE clause is an optional part of a SELECT statement. Cursors are read-only by default. The FOR UPDATE clause specifies that the cursor should be updatable, and enforces a check during compilation that the SELECT statement meets the requirements for an updatable cursor. For more information about updatability, see Requirements for updatable cursors and updatable ResultSets.
Syntax
FOR { READ ONLY | FETCH ONLY | UPDATE [ OF Simple-column-Name [ , Simple-column-Name]* ] }
Simple-column-Name refers to the names visible for the table specified in the FROM clause of the underlying query.
Note: The use of the FOR UPDATE clause is not mandatory to obtain an updatable JDBC ResultSet. As long as the statement used to generate the JDBC ResultSet meets the requirements for updatable cursor, it is sufficient for the JDBC Statement that generates the JDBC ResultSet to have concurrency mode ResultSet.CONCUR_UPDATABLE for the ResultSet to be updatable.
The optimizer is able to use an index even if the column in the index is being updated.
SELECT RECEIVED, SOURCE, SUBJECT, NOTE_TEXT FROM SAMP.IN_TRAY FOR UPDATE
For information about how indexes affect performance, see Tuning Java DB.
FROM clause
The FROM clause is a mandatory clause in a SelectExpression. It specifies the tables (TableExpression) from which the other clauses of the query can access columns for use in expressions.
Syntax
FROM TableExpression [ , TableExpression ] *
SELECT Cities.city_id FROM Cities WHERE city_id < 5 -- other types of TableExpressions SELECT TABLENAME, ISINDEX FROM SYS.SYSTABLES T, SYS.SYSCONGLOMERATES C WHERE T.TABLEID = C.TABLEID ORDER BY TABLENAME, ISINDEX -- force the join order SELECT * FROM Flights, FlightAvailability WHERE FlightAvailability.flight_id = Flights.flight_id AND FlightAvailability.segment_number = Flights.segment_number AND Flights.flight_id < 'AA1115' -- a TableExpression can be a joinOperation. Therefore -- you can have multiple join operations in a FROM clause SELECT COUNTRIES.COUNTRY, CITIES.CITY_NAME, FLIGHTS.DEST_AIRPORT FROM COUNTRIES LEFT OUTER JOIN CITIES ON COUNTRIES.COUNTRY_ISO_CODE = CITIES.COUNTRY_ISO_CODE LEFT OUTER JOIN FLIGHTS ON Cities.AIRPORT = FLIGHTS.DEST_AIRPORT
GROUP BY clause
A GROUP BY clause, part of a SelectExpression, groups a result into subsets that have matching values for one or more columns. In each group, no two rows have the same value for the grouping column or columns. NULLs are considered equivalent for grouping purposes.
You typically use a GROUP BY clause in conjunction with an aggregate expression.
Syntax
GROUP BY column-Name [ , column-Name ] *
column-Name must be a column from the current scope of the query; there can be no columns from a query block outside the current scope. For example, if a GROUP BY clause is in a subquery, it cannot refer to columns in the outer query.
SelectItems in the SelectExpression with a GROUP BY clause must contain only aggregates or grouping columns.
-- find the average flying_times of flights grouped by -- airport SELECT AVG (flying_time), orig_airport FROM Flights GROUP BY orig_airport SELECT MAX(city_name), region FROM Cities, Countries WHERE Cities.country_ISO_code = Countries.country_ISO_code GROUP BY region -- group by an a smallint SELECT ID, AVG(SALARY) FROM SAMP.STAFF GROUP BY ID -- Get the AVGSALARY and EMPCOUNT columns, and the DEPTNO column using the AS clause -- And group by the WORKDEPT column using the correlation name OTHERS SELECT OTHERS.WORKDEPT AS DEPTNO, AVG(OTHERS.SALARY) AS AVGSALARY, COUNT(*) AS EMPCOUNT FROM SAMP.EMPLOYEE OTHERS GROUP BY OTHERS.WORKDEPT
HAVING clause
A HAVING clause restricts the results of a GROUP BY in a SelectExpression. The HAVING clause is applied to each group of the grouped table, much as a WHERE clause is applied to a select list. If there is no GROUP BY clause, the HAVING clause is applied to the entire result as a single group. The SELECT clause cannot refer directly to any column that does not have a GROUP BY clause. It can, however, refer to constants, aggregates, and special registers.
Syntax
HAVING searchCondition
The searchCondition, which is a specialized booleanExpression, can contain only grouping columns (see GROUP BY clause), columns that are part of aggregate expressions, and columns that are part of a subquery. For example, the following query is illegal, because the column SALARY is not a grouping column, it does not appear within an aggregate, and it is not within a subquery:
-- SELECT COUNT(*) -- FROM SAMP.STAFF -- GROUP BY ID -- HAVING SALARY > 15000
Aggregates in the HAVING clause do not need to appear in the SELECT list. If the HAVING clause contains a subquery, the subquery can refer to the outer query block if and only if it refers to a grouping column.
-- Find the total number of economy seats taken on a flight, -- grouped by airline, -- only when the group has at least 2 records. SELECT SUM(ECONOMY_SEATS_TAKEN), AIRLINE_FULL FROM FLIGHTAVAILABILITY, AIRLINES WHERE SUBSTR(FLIGHTAVAILABILITY.FLIGHT_ID, 1, 2) = AIRLINE GROUP BY AIRLINE_FULL HAVING COUNT(*) > 1
ORDER BY clause
The ORDER BY clause is an optional element of a SELECT statement. An ORDER BY clause allows you to specify the order in which rows appear in the ResultSet.
Syntax
ORDER BY { column-Name | ColumnPosition | Expression } [ ASC | DESC ] [ , column-Name | ColumnPosition | Expression [ ASC | DESC ] ] *
column-Name
Refers to the names visible from the SelectItems in the underlying query of the SELECT statement. The column-Name that you specify in the ORDER BY clause does not need to be the SELECT list.
ColumnPosition
An integer that identifies the number of the column in the SelectItems in the underlying query of the SELECT statement. ColumnPosition must be greater than 0 and not greater than the number of columns in the result table. In other words, if you want to order by a column, that column must be specified in the SELECT list.
Expression
A sort key expression, such as numeric, string, and datetime expressions. Expression can also be a row value expression such as a scalar subquery or case expression.
ASC
Specifies that the results should be returned in ascending order. If the order is not specified, ASC is the default.
DESC
Specifies that the results should be returned in descending order.
Notes
 
If SELECT DISTINCT is specified or if the SELECT statement contains a GROUP BY clause, the ORDER BY columns must be in the SELECT list.
 
An ORDER BY clause prevents a SELECT statement from being an updatable cursor. For more information, see Requirements for updatable cursors and updatable ResultSets. For example, if an INTEGER column contains integers, NULL is considered greater than 1 for purposes of sorting. In other words, NULL values are sorted high.
Example using a correlation name
You can sort the result set by a correlation name, if the correlation name is specified in the select list. For example, to return from the CITIES database all of the entries in the CITY_NAME and COUNTRY columns, where the COUNTRY column has the correlation name NATION, you specify this SELECT statement:
SELECT CITY_NAME, COUNTRY AS NATION FROM CITIES ORDER BY NATION
Example using a numeric expression
You can sort the result set by a numeric expression, for example:
SELECT name, salary, bonus FROM employee ORDER BY salary+bonus
In this example, the salary and bonus columns are DECIMAL data types.
Example using a function
You can sort the result set by invoking a function, for example:
SELECT i, len FROM measures ORDER BY sin(i)
The result offset and fetch first clauses
The result offset clause provides a way to skip the N first rows in a result set before starting to return any rows. The fetch first clause, which can be combined with the result offset clause if desired, limits the number of rows returned in the result set. The fetch first clause can sometimes be useful for retrieving only a few rows from an otherwise large result set, usually in combination with an ORDER BY clause. The use of this clause can give efficiency benefits. In addition, it can make programming the application simpler.
Syntax
OFFSET integer-literal {ROW | ROWS}
FETCH { FIRST | NEXT } [integer-literal] {ROW | ROWS} ONLY
ROW is synonymous with ROWS and FIRST is synonymous with NEXT.
For the result offset clause the integer literal must be equal to 0 (default if the clause is not given), or positive. If it is larger than the number of rows in the underlying result set, no rows are returned.
For the fetch first clause, the literal must be 1 or higher. The literal can be omitted, in which case it defaults to 1. If the clause is omitted entirely, all rows (or those rows remaining if a result offset clause is also given) will be returned.
Examples
-- Fetch the first row of T SELECT * FROM T FETCH FIRST ROW ONLY -- Sort T using column I, then fetch rows 11 through 20 of the sorted -- rows (inclusive) SELECT * FROM T ORDER BY I OFFSET 10 ROWS FETCH NEXT 10 ROWS ONLY -- Skip the first 100 rows of T -- If the table has fewer than 101 records, an empty result set is -- returned SELECT * FROM T OFFSET 100 ROWS
Note: Make sure to specify the ORDER BY clause if you expect to retrieve a sorted result set. If you do not use an ORDER BY clause, the result set that is retrieved will typically have the order in which the records were inserted.
WHERE clause
A WHERE clause is an optional part of a SelectExpression,DELETE statement, or UPDATE statement. The WHERE clause lets you select rows based on a boolean expression. Only rows for which the expression evaluates to TRUE are returned in the result, or, in the case of a DELETE statement, deleted, or, in the case of an UPDATE statement, updated.
Syntax
Boolean expressions are allowed in the WHERE clause. Most of the general expressions listed in Table of general expressions, can result in a boolean value.
In addition, there are the more common boolean expressions. Specific boolean operators listed in Table 10, take one or more operands; the expressions return a boolean value.
Example
-- find the flights where no business-class seats have -- been booked SELECT * FROM FlightAvailability WHERE business_seats_taken IS NULL OR business_seats_taken = 0 -- Join the EMP_ACT and EMPLOYEE tables -- select all the columns from the EMP_ACT table and -- add the employee's surname (LASTNAME) from the EMPLOYEE table -- to each row of the result. SELECT SAMP.EMP_ACT.*, LASTNAME FROM SAMP.EMP_ACT, SAMP.EMPLOYEE WHERE EMP_ACT.EMPNO = EMPLOYEE.EMPNO -- Determine the employee number and salary of sales representatives -- along with the average salary and head count of their departments. -- This query must first create a new-column-name specified in the AS clause -- which is outside the fullselect (DINFO) -- in order to get the AVGSALARY and EMPCOUNT columns, -- as well as the DEPTNO column that is used in the WHERE clause SELECT THIS_EMP.EMPNO, THIS_EMP.SALARY, DINFO.AVGSALARY, DINFO.EMPCOUNT FROM EMPLOYEE THIS_EMP, (SELECT OTHERS.WORKDEPT AS DEPTNO, AVG(OTHERS.SALARY) AS AVGSALARY, COUNT(*) AS EMPCOUNT FROM EMPLOYEE OTHERS GROUP BY OTHERS.WORKDEPT )AS DINFO WHERE THIS_EMP.JOB = 'SALESREP' AND THIS_EMP.WORKDEPT = DINFO.DEPTNO
WHERE CURRENT OF clause
The WHERE CURRENT OF clause is a clause in some UPDATE and DELETE statements. It allows you to perform positioned updates and deletes on updatable cursors. For more information about updatable cursors, see SELECT statement.
Syntax
WHERE CURRENT OF cursor-Name
Statement s = conn.createStatement(); s.setCursorName("AirlinesResults"); ResultSet rs = conn.executeQuery( "SELECT Airline, basic_rate " + "FROM Airlines FOR UPDATE OF basic_rate"); Statement s2 = conn.createStatement(); s2.executeUpdate("UPDATE Airlines SET basic_rate = basic_rate " + "+ .25 WHERE CURRENT OF AirlinesResults");
SQL expressions
Syntax for many statements and expressions includes the term Expression, or a term for a specific kind of expression such as TableSubquery. Expressions are allowed in these specified places within statements.
Some locations allow only a specific type of expression or one with a specific property. If not otherwise specified, an expression is permitted anywhere the word Expression appears in the syntax. This includes:
Of course, many other statements include these elements as building blocks, and so allow expressions as part of these elements.
The following tables list all the possible SQL expressions and indicate where the expressions are allowed.
General expressions
General expressions are expressions that might result in a value of any type.
Table 2. Table of general expressions
Expression Type
Explanation
Column reference
A column-Name that references the value of the column made visible to the expression containing the Column reference.
You must qualify the column-Name by the table name or correlation name if it is ambiguous.
The qualifier of a column-Name must be the correlation name, if a correlation name is given to a table that is in a FROM clause. The table name is no longer visible as a column-Name qualifier once it has been aliased by a correlation name.
Allowed in SelectExpressions, UPDATE statements, and the WHERE clauses of data manipulation statements.
Constant
Most built-in data types typically have constants associated with them (as shown in Data types).
NULL
NULL is an untyped constant representing the unknown value.
Allowed in CAST expressions or in INSERT VALUES lists and UPDATE SET clauses. Using it in a CAST expression gives it a specific data type.
Dynamic parameter
A dynamic parameter is a parameter to an SQL statement for which the value is not specified when the statement is created. Instead, the statement has a question mark (?) as a placeholder for each dynamic parameter. See Dynamic parameters.
Dynamic parameters are permitted only in prepared statements. You must specify values for them before the prepared statement is executed. The values specified must match the types expected.
Allowed anywhere in an expression where the data type can be easily deduced. See Dynamic parameters.
CAST expression
Lets you specify the type of NULL or of a dynamic parameter or convert a value to another type. See CAST function.
Scalar subquery
Subquery that returns a single row with a single column. See ScalarSubquery.
Table subquery
Subquery that returns more than one column and more than one row. See TableSubquery.
Allowed as a tableExpression in a FROM clause and with EXISTS, IN, and quantified comparisons.
Conditional expression
A conditional expression chooses an expression to evaluate based on a boolean test.
Boolean expressions
Boolean expressions are expressions that result in boolean values. Most general expressions can result in boolean values. Boolean expressions commonly used in a WHERE clause are made of operands operated on by SQL operators. See SQL Boolean Operators.
Numeric expressions
Numeric expressions are expressions that result in numeric values. Most of the general expressions can result in numeric values. Numeric values have one of the following types:
 
BIGINT
 
DECIMAL
 
DOUBLE PRECISION
 
INTEGER
 
REAL
 
SMALLINT
Table 3. Table of numeric expressions
Expression Type
Explanation
+, -, *, /, unary + and - expressions
Evaluate the expected math operation on the operands. If both operands are the same type, the result type is not promoted, so the division operator on integers results in an integer that is the truncation of the actual numeric result. When types are mixed, they are promoted as described in Data types.
Unary + is a noop (i.e., +4 is the same as 4). Unary - is the same as multiplying the value by -1, effectively changing its sign.
AVG
Returns the average of a set of numeric values. AVG function
SUM
Returns the sum of a set of numeric values. SUM function
LENGTH
Returns the number of characters in a character or bit string. See LENGTH function.
LOWER
COUNT
Returns the count of a set of values. See COUNT function, COUNT(*) function.
Character expressions
Character expressions are expressions that result in a CHAR or VARCHAR value. Most general expressions can result in a CHAR or VARCHAR value.
Table 4. Table of character expressions
Expression Type
Explanation
A CHAR or VARCHAR value that uses wildcards.
The wildcards % and _ make a character string a pattern against which the LIKE operator can look for a match.
Concatenation expression
In a concatenation expression, the concatenation operator, "||", concatenates its right operand to the end of its left operand. Operates on character and bit strings. See Concatenation operator.
Built-in string functions
The built-in string functions act on a String and return a string. See LTRIM function, LCASE or LOWER function, RTRIM function, TRIM function, SUBSTR function, and UCASE or UPPER function.
USER functions
User functions return information about the current user as a String. See CURRENT_USER function, SESSION_USER function, and .
Date and time expressions
A date or time expression results in a DATE, TIME, or TIMESTAMP value. Most of the general expressions can result in a date or time value.
Table 5. Table of date and time expressions
Expression type
Explanation
CURRENT_DATE
Returns the current date. See CURRENT_DATE function.
CURRENT_TIME
Returns the current time. See CURRENT_TIME function.
CURRENT_TIMESTAMP
Returns the current timestamp. See CURRENT_TIMESTAMP function.
SelectExpression
A SelectExpression is the basic SELECT-FROM-WHERE construct used to build a table value based on filtering and projecting values from other tables.
Syntax
SELECT [ DISTINCT | ALL ] SelectItem [ , SelectItem ]* FROM clause [ WHERE clause] [ GROUP BY clause ] [ HAVING clause ]
SelectItem:
{ * | { table-Name | correlation-Name } .* | Expression [AS Simple-column-Name] }
The SELECT clause contains a list of expressions and an optional quantifier that is applied to the results of the FROM clause and the WHERE clause. If DISTINCT is specified, only one copy of any row value is included in the result. Nulls are considered duplicates of one another for the purposes of DISTINCT. If no quantifier, or ALL, is specified, no rows are removed from the result in applying the SELECT clause (ALL is the default).
A SelectItem projects one or more result column values for a table result being constructed in a SelectExpression.
The result of the FROM clause is the cross product of the FROM items. The WHERE clause can further qualify this result.
The WHERE clause causes rows to be filtered from the result based on a boolean expression. Only rows for which the expression evaluates to TRUE are returned in the result.
The GROUP BY clause groups rows in the result into subsets that have matching values for one or more columns. GROUP BY clauses are typically used with aggregates.
If there is a GROUP BY clause, the SELECT clause must contain only aggregates or grouping columns. If you want to include a non-grouped column in the SELECT clause, include the column in an aggregate expression. For example:
-- List head count of each department, -- the department number (WORKDEPT), and the average departmental salary (SALARY) -- for all departments in the EMPLOYEE table. -- Arrange the result table in ascending order by average departmental salary. SELECT COUNT(*),WORK_DEPT,AVG(SALARY) FROM EMPLOYEE GROUP BY WORK_DEPT ORDER BY 3
If there is no GROUP BY clause, but a SelectItem contains an aggregate not in a subquery, the query is implicitly grouped. The entire table is the single group.
The HAVING clause restricts a grouped table, specifying a search condition (much like a WHERE clause) that can refer only to grouping columns or aggregates from the current scope. The HAVING clause is applied to each group of the grouped table. If the HAVING clause evaluates to TRUE, the row is retained for further processing. If the HAVING clause evaluates to FALSE or NULL, the row is discarded. If there is a HAVING clause but no GROUP BY, the table is implicitly grouped into one group for the entire table.
Derby processes a SelectExpression in the following order:
 
FROM clause
 
WHERE clause
 
GROUP BY (or implicit GROUP BY)
 
HAVING clause
 
SELECT clause
The result of a SelectExpression is always a table.
When a query does not have a FROM clause (when you are constructing a value, not getting data out of a table), you use a VALUES expression, not a SelectExpression. For example:
VALUES CURRENT_TIMESTAMP
The * wildcard
* expands to all columns in the tables in the associated FROM clause.
table-Name.* and correlation-Name.* expand to all columns in the identified table. That table must be listed in the associated FROM clause.
Naming columns
You can name a SelectItem column using the AS clause. If a column of a SelectItem is not a simple ColumnReference expression or named with an AS clause, it is given a generated unique name.
These column names are useful in several cases:
 
They are made available on the JDBC ResultSetMetaData.
 
They are used as the names of the columns in the resulting table when the SelectExpression is used as a table subquery in a FROM clause.
 
They are used in the ORDER BY clause as the column names available for sorting.
-- this example shows SELECT-FROM-WHERE -- with an ORDER BY clause -- and correlation-Names for the tables SELECT CONSTRAINTNAME, COLUMNNAME FROM SYS.SYSTABLES t, SYS.SYSCOLUMNS col, SYS.SYSCONSTRAINTS cons, SYS.SYSCHECKS checks WHERE t.TABLENAME = 'FLIGHTS' AND t.TABLEID = col. REFERENCEID AND t.TABLEID = cons.TABLEID AND cons.CONSTRAINTID = checks.CONSTRAINTID ORDER BY CONSTRAINTNAME -- This example shows the use of the DISTINCT clause SELECT DISTINCT ACTNO FROM EMP_ACT -- This example shows how to rename an expression -- Using the EMPLOYEE table, list the department number (WORKDEPT) and -- maximum departmental salary (SALARY) renamed as BOSS -- for all departments whose maximum salary is less than the -- average salary in all other departments. SELECT WORKDEPT AS DPT, MAX(SALARY) AS BOSS FROM EMPLOYEE EMP_COR GROUP BY WORKDEPT HAVING MAX(SALARY) < (SELECT AVG(SALARY) FROM EMPLOYEE WHERE NOT WORKDEPT = EMP_COR.WORKDEPT) ORDER BY BOSS
TableExpression
A TableExpression specifies a table, view, or function in a FROM clause. It is the source from which a SelectExpression selects a result.
A correlation name can be applied to a table in a TableExpression so that its columns can be qualified with that name. If you do not supply a correlation name, the table name qualifies the column name. When you give a table a correlation name, you cannot use the table name to qualify columns. You must use the correlation name when qualifying column names.
No two items in the FROM clause can have the same correlation name, and no correlation name can be the same as an unqualified table name specified in that FROM clause.
In addition, you can give the columns of the table new names in the AS clause. Some situations in which this is useful:
 
When a VALUES expression is used as a TableSubquery, since there is no other way to name the columns of a VALUES expression.
 
When column names would otherwise be the same as those of columns in other tables; renaming them means you don't have to qualify them.
The Query in a TableSubquery appearing in a FromItem can contain multiple columns and return multiple rows. See TableSubquery.
For information about the optimizer overrides you can specify, see Tuning Java DB.
Syntax
{ TableViewOrFunctionExpression | JOIN operation }
Example
-- SELECT from a Join expression SELECT E.EMPNO, E.LASTNAME, M.EMPNO, M.LASTNAME FROM EMPLOYEE E LEFT OUTER JOIN DEPARTMENT INNER JOIN EMPLOYEE M ON MGRNO = M.EMPNO ON E.WORKDEPT = DEPTNO
TableViewOrFunctionExpression
TableFunctionInvocation:
TABLE function-name( [ [ function-arg ] [, function-arg ]* ] )
Note that when you invoke a table function, you must bind it to a correlation name. For example:
SELECT s.* FROM TABLE( externalEmployees( 42 ) ) s
VALUES expression
The VALUES expression allows construction of a row or a table from other values. A VALUES expression can be used in all the places where a query can, and thus can be used in any of the following ways:
 
As a statement that returns a ResultSet
 
Within expressions and statements wherever subqueries are permitted
 
As the source of values for an INSERT statement (in an INSERT statement, you normally use a VALUES expression when you do not use a SelectExpression)
Syntax
{ VALUES ( Value {, Value }* ) [ , ( Value {, Value }* ) ]* | VALUES Value [ , Value ]* }
where Value is defined as
Expression | DEFAULT
The first form constructs multi-column rows. The second form constructs single-column rows, each expression being the value of the column of the row.
The DEFAULT keyword is allowed only if the VALUES expression is in an INSERT statement. Specifying DEFAULT for a column inserts the column's default value into the column. Another way to insert the default value into the column is to omit the column from the column list and only insert values into other columns in the table.
Examples
-- 3 rows of 1 column VALUES (1),(2),(3) -- 3 rows of 1 column VALUES 1, 2, 3 -- 1 row of 3 columns VALUES (1, 2, 3) -- 3 rows of 2 columns VALUES (1,21),(2,22),(3,23) -- constructing a derived table VALUES ('orange', 'orange'), ('apple', 'red'), ('banana', 'yellow') -- Insert two new departments using one statement into the DEPARTMENT table, -- but do not assign a manager to the new department. INSERT INTO DEPARTMENT (DEPTNO, DEPTNAME, ADMRDEPT) VALUES ('B11', 'PURCHASING', 'B01'), ('E41', 'DATABASE ADMINISTRATION', 'E01') -- insert a row with a DEFAULT value for the MAJPROJ column INSERT INTO PROJECT (PROJNO, PROJNAME, DEPTNO, RESPEMP, PRSTDATE, MAJPROJ) VALUES ('PL2101', 'ENSURE COMPAT PLAN', 'B01', '000020', CURRENT_DATE, DEFAULT) -- using a built-in function VALUES CURRENT_DATE -- getting the value of an arbitrary expression VALUES (3*29, 26.0E0/3) -- getting a value returned by a built-in function values char(1)
Expression precedence
Precedence of operations from highest to lowest is:
 
(), ?, Constant (including sign), NULL, ColumnReference, ScalarSubquery, CAST
 
LENGTH, CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, and other built-ins
 
unary + and -
 
*, /, || (concatenation)
 
binary + and -
 
comparisons, quantified comparisons, EXISTS, IN, IS NULL, LIKE, BETWEEN, IS
 
NOT
 
AND
 
OR
You can explicitly specify precedence by placing expressions within parentheses. An expression within parentheses is evaluated before any operations outside the parentheses are applied to it.
Example
(3+4)*9 (age < 16 OR age > 65) AND employed = TRUE
Boolean expressions
Boolean expressions are allowed in WHERE clauses and in check constraints. Boolean expressions in check constraints have limitations not noted here; see CONSTRAINT clause for more information. Boolean expressions in a WHERE clause have a highly liberal syntax; see WHERE clause, for example.
A boolean expression can include a boolean operator or operators. These are listed in SQL Boolean Operators.
Table 6. SQL Boolean Operators
Operator
Explanation and Example
Syntax
AND, OR, NOT
Evaluate any operand(s) that are boolean expressions
(orig_airport = 'SFO') OR (dest_airport = 'GRU') -- returns true
{ Expression AND Expression | Expression OR Expression | NOT Expression }
Comparisons
<, =, >, <=, >=, <> are applicable to all of the built-in types.
DATE('1998-02-26') < DATE('1998-03-01') -- returns true
Expression { < | = | > | <= | >= | <> } Expression
IS NULL, IS NOT NULL
Test whether the result of an expression is null or not.
WHERE MiddleName IS NULL
Expression IS [ NOT ] NULL
LIKE
Attempts to match a character expression to a character pattern, which is a character string that includes one or more wildcards.
% matches any number (zero or more) of characters in the corresponding position in first character expression.
_ matches one character in the corresponding position in the character expression.
Any other character matches only that character in the corresponding position in the character expression.
city LIKE 'Sant_'
To treat % or _ as constant characters, escape the character with an optional escape character, which you specify with the ESCAPE clause.
SELECT a FROM tabA WHERE a LIKE '%=_' ESCAPE '='
Note: When LIKE comparisons are used,Derby compares one character at a time for non-metacharacters. This is different than the way Derby processes = comparisons. The comparisons with the = operator compare the entire character string on left side of the = operator with the entire character string on the right side of the = operator. For more information, see Character-based collation in Derby in the Java DB Developer's Guide.
CharacterExpression [ NOT ] LIKE CharacterExpression WithWildCard [ ESCAPE 'escapeCharacter']
BETWEEN
Tests whether the first operand is between the second and third operands. The second operand must be less than the third operand. Applicable only to types to which <= and >= can be applied.
WHERE booking_date BETWEEN DATE('1998-02-26') AND DATE('1998-03-01')
Expression [ NOT ] BETWEEN Expression AND Expression
IN
Operates on table subquery or list of values. Returns TRUE if the left expression's value is in the result of the table subquery or in the list of values. Table subquery can return multiple rows but must return a single column.
WHERE booking_date NOT IN (SELECT booking_date FROM HotelBookings WHERE rooms_available = 0)
{ Expression [ NOT ] IN TableSubquery | Expression [ NOT ] IN ( Expression [, Expression ]* ) }
EXISTS
Operates on a table subquery. Returns TRUE if the table subquery returns any rows, and FALSE if it returns no rows. Table subquery can return multiple columns (only if you use * to denote multiple columns) and rows.
WHERE EXISTS (SELECT * FROM Flights WHERE dest_airport = 'SFO' AND orig_airport = 'GRU')
[NOT] EXISTS TableSubquery
Quantified comparison
A quantified comparison is a comparison operator (<, =, >, <=, >=, <>) with ALL or ANY or SOME applied.
Operates on table subqueries, which can return multiple rows but must return a single column.
If ALL is used, the comparison must be true for all values returned by the table subquery. If ANY or SOME is used, the comparison must be true for at least one value of the table subquery. ANY and SOME are equivalent.
WHERE normal_rate < ALL (SELECT budget/550 FROM Groups)
Expression ComparisonOperator { ALL | ANY | SOME } TableSubquery
Dynamic parameters
You can prepare statements that are allowed to have parameters for which the value is not specified when the statement is prepared using PreparedStatement methods in the JDBC API. These parameters are called dynamic parameters and are represented by a ?.
The JDBC API documents refer to dynamic parameters as IN, INOUT, or OUT parameters. In SQL, they are always IN parameters.
New: Derby supports the interface ParameterMetaData, new in JDBC 3.0. This interface describes the number, type, and properties of prepared statement parameters. See the Java DB Developer's Guide for more information.
You must specify values for them before executing the statement. The values specified must match the types expected.
Dynamic parameters example
PreparedStatement ps2 = conn.prepareStatement( "UPDATE HotelAvailability SET rooms_available = " + "(rooms_available - ?) WHERE hotel_id = ? " + "AND booking_date BETWEEN ? AND ?"); -- this sample code sets the values of dynamic parameters -- to be the values of program variables ps2.setInt(1, numberRooms); ps2.setInt(2, theHotel.hotelId); ps2.setDate(3, arrival); ps2.setDate(4, departure); updateCount = ps2.executeUpdate();
Where dynamic parameters are allowed
You can use dynamic parameters anywhere in an expression where their data type can be easily deduced.
1.
 
Use as the first operand of BETWEEN is allowed if one of the second and third operands is not also a dynamic parameter. The type of the first operand is assumed to be the type of the non-dynamic parameter, or the union result of their types if both are not dynamic parameters.
WHERE ? BETWEEN DATE('1996-01-01') AND ? -- types assumed to be DATE
2.
 
Use as the second or third operand of BETWEEN is allowed. Type is assumed to be the type of the left operand.
WHERE DATE('1996-01-01') BETWEEN ? AND ? -- types assumed to be DATE
3.
 
Use as the left operand of an IN list is allowed if at least one item in the list is not itself a dynamic parameter. Type for the left operand is assumed to be the union result of the types of the non-dynamic parameters in the list.
WHERE ? NOT IN (?, ?, 'Santiago') -- types assumed to be CHAR
4.
 
Use in the values list in an IN predicate is allowed if the first operand is not a dynamic parameter or its type was determined in the previous rule. Type of the dynamic parameters appearing in the values list is assumed to be the type of the left operand.
WHERE FloatColumn IN (?, ?, ?) -- types assumed to be FLOAT
5.
 
For the binary operators +, -, *, /, AND, OR, <, >, =, <>, <=, and >=, use of a dynamic parameter as one operand but not both is permitted. Its type is taken from the other side.
WHERE ? < CURRENT_TIMESTAMP -- type assumed to be a TIMESTAMP
6.
 
Use in a CAST is always permitted. This gives the dynamic parameter a type.
CALL valueOf(CAST (? AS VARCHAR(10)))
7.
 
Use on either or both sides of LIKE operator is permitted. When used on the left, the type of the dynamic parameter is set to the type of the right operand, but with the maximum allowed length for the type. When used on the right, the type is assumed to be of the same length and type as the left operand. (LIKE is permitted on CHAR and VARCHAR types; see Concatenation operator for more information.)
WHERE ? LIKE 'Santi%' -- type assumed to be CHAR with a length of -- java.lang.Integer.MAX_VALUE
8.
 
A ? parameter is allowed by itself on only one side of the || operator. That is, "? || ?" is not allowed. The type of a ? parameter on one side of a || operator is determined by the type of the expression on the other side of the || operator. If the expression on the other side is a CHAR or VARCHAR, the type of the parameter is VARCHAR with the maximum allowed length for the type. If the expression on the other side is a CHAR FOR BIT DATA or VARCHAR FOR BIT DATA type, the type of the parameter is VARCHAR FOR BIT DATA with the maximum allowed length for the type.
SELECT BITcolumn || ? FROM UserTable -- Type assumed to be CHAR FOR BIT DATA of length specified for BITcolumn
9.
 
In a conditional expression, which uses a ?, use of a dynamic parameter (which is also represented as a ?) is allowed. The type of a dynamic parameter as the first operand is assumed to be boolean. Only one of the second and third operands can be a dynamic parameter, and its type will be assumed to be the same as that of the other (that is, the third and second operand, respectively).
SELECT c1 IS NULL ? ? : c1 -- allows you to specify a "default" value at execution time -- dynamic parameter assumed to be the type of c1 -- you cannot have dynamic parameters on both sides -- of the :
10.
 
A dynamic parameter is allowed as an item in the values list or select list of an INSERT statement. The type of the dynamic parameter is assumed to be the type of the target column.
INSERT INTO t VALUES (?) -- dynamic parameter assumed to be the type -- of the only column in table t INSERT INTO t SELECT ? FROM t2 -- not allowed
11.
 
A ? parameter in a comparison with a subquery takes its type from the expression being selected by the subquery. For example:
SELECT * FROM tab1 WHERE ? = (SELECT x FROM tab2) SELECT * FROM tab1 WHERE ? = ANY (SELECT x FROM tab2) -- In both cases, the type of the dynamic parameter is -- assumed to be the same as the type of tab2.x.
12.
 
A dynamic parameter is allowed as the value in an UPDATE statement. The type of the dynamic parameter is assumed to be the type of the column in the target table.
UPDATE t2 SET c2 =? -- type is assumed to be type of c2
13.
 
Dynamic parameters are allowed as the operand of the unary operators - or +. For example:
CREATE TABLE t1 (c11 INT, c12 SMALLINT, c13 DOUBLE, c14 CHAR(3)) SELECT * FROM t1 WHERE c11 BETWEEN -? AND +? -– The type of both of the unary operators is INT -- based on the context in which they are used (that is, -- because c11 is INT, the unary parameters also get the -- type INT.
14.
 
LENGTH allow a dynamic parameter. The type is assumed to be a maximum length VARCHAR type.
SELECT LENGTH(?)
15.
 
Qualified comparisons.
? = SOME (SELECT 1 FROM t) -- is valid. Dynamic parameter assumed to be INTEGER type 1 = SOME (SELECT ? FROM t) -- is valid. Dynamic parameter assumed to be INTEGER type.
16.
 
A dynamic parameter is allowed as the left operand of an IS expression and is assumed to be a boolean.
Once the type of a dynamic parameter is determined based on the expression it is in, that expression is allowed anywhere it would normally be allowed if it did not include a dynamic parameter.
JOIN operations
The JOIN operations, which are among the possible TableExpressions in a FROM clause, perform joins between two tables. (You can also perform a join between two tables using an explicit equality test in a WHERE clause, such as "WHERE t1.col1 = t2.col2".)
Syntax
JOIN Operation
The JOIN operations are:
 
INNER JOIN operation
Specifies a join between two tables with an explicit join clause. See INNER JOIN operation.
 
LEFT OUTER JOIN operation
Specifies a join between two tables with an explicit join clause, preserving unmatched rows from the first table. See LEFT OUTER JOIN operation.
 
RIGHT OUTER JOIN operation
Specifies a join between two tables with an explicit join clause, preserving unmatched rows from the second table. See RIGHT OUTER JOIN operation.
In all cases, you can specify additional restrictions on one or both of the tables being joined in outer join clauses or in the WHERE clause.
JOIN expressions and query optimization
For information on which types of joins are optimized, see Tuning Java DB.
INNER JOIN operation
An INNER JOIN is a JOIN operation that allows you to specify an explicit join clause.
Syntax
TableExpression [ INNER ] JOIN TableExpression { ON booleanExpression }
You can specify the join clause by specifying ON with a boolean expression.
The scope of expressions in the ON clause includes the current tables and any tables in outer query blocks to the current SELECT. In the following example, the ON clause refers to the current tables:
SELECT * FROM SAMP.EMPLOYEE INNER JOIN SAMP.STAFF ON EMPLOYEE.SALARY < STAFF.SALARY
The ON clause can reference tables not being joined and does not have to reference either of the tables being joined (though typically it does).
-- Join the EMP_ACT and EMPLOYEE tables -- select all the columns from the EMP_ACT table and -- add the employee's surname (LASTNAME) from the EMPLOYEE table -- to each row of the result SELECT SAMP.EMP_ACT.*, LASTNAME FROM SAMP.EMP_ACT JOIN SAMP.EMPLOYEE ON EMP_ACT.EMPNO = EMPLOYEE.EMPNO -- Join the EMPLOYEE and DEPARTMENT tables, -- select the employee number (EMPNO), -- employee surname (LASTNAME), -- department number (WORKDEPT in the EMPLOYEE table and DEPTNO in the -- DEPARTMENT table) -- and department name (DEPTNAME) -- of all employees who were born (BIRTHDATE) earlier than 1930. SELECT EMPNO, LASTNAME, WORKDEPT, DEPTNAME FROM SAMP.EMPLOYEE JOIN SAMP.DEPARTMENT ON WORKDEPT = DEPTNO AND YEAR(BIRTHDATE) < 1930 -- Another example of "generating" new data values, -- using a query which selects from a VALUES clause (which is an -- alternate form of a fullselect). -- This query shows how a table can be derived called "X" -- having 2 columns "R1" and "R2" and 1 row of data SELECT * FROM (VALUES (3, 4), (1, 5), (2, 6)) AS VALUESTABLE1(C1, C2) JOIN (VALUES (3, 2), (1, 2), (0, 3)) AS VALUESTABLE2(c1, c2) ON VALUESTABLE1.c1 = VALUESTABLE2.c1 -- This results in: -- C1 |C2 |C1 |2 -- ----------------------------------------------- -- 3 |4 |3 |2 -- 1 |5 |1 |2 -- List every department with the employee number and -- last name of the manager SELECT DEPTNO, DEPTNAME, EMPNO, LASTNAME FROM DEPARTMENT INNER JOIN EMPLOYEE ON MGRNO = EMPNO -- List every employee number and last name -- with the employee number and last name of their manager SELECT E.EMPNO, E.LASTNAME, M.EMPNO, M.LASTNAME FROM EMPLOYEE E INNER JOIN DEPARTMENT INNER JOIN EMPLOYEE M ON MGRNO = M.EMPNO ON E.WORKDEPT = DEPTNO
LEFT OUTER JOIN operation
A LEFT OUTER JOIN is one of the JOIN operations that allow you to specify a join clause. It preserves the unmatched rows from the first (left) table, joining them with a NULL row in the shape of the second (right) table.
Syntax
TableExpression LEFT [ OUTER ] JOIN TableExpression { ON booleanExpression }
The scope of expressions in either the ON clause includes the current tables and any tables in query blocks outer to the current SELECT. The ON clause can reference tables not being joined and does not have to reference either of the tables being joined (though typically it does).
Example 1
--match cities to countries in Asia SELECT CITIES.COUNTRY, CITIES.CITY_NAME, REGION FROM Countries LEFT OUTER JOIN Cities ON CITIES.COUNTRY_ISO_CODE = COUNTRIES.COUNTRY_ISO_CODE WHERE REGION = 'Asia' -- use the synonymous syntax, LEFT JOIN, to achieve exactly -- the same results as in the example above SELECT COUNTRIES.COUNTRY, CITIES.CITY_NAME,REGION FROM COUNTRIES LEFT JOIN CITIES ON CITIES.COUNTRY_ISO_CODE = COUNTRIES.COUNTRY_ISO_CODE WHERE REGION = 'Asia'
Example 2
-- Join the EMPLOYEE and DEPARTMENT tables, -- select the employee number (EMPNO), -- employee surname (LASTNAME), -- department number (WORKDEPT in the EMPLOYEE table -- and DEPTNO in the DEPARTMENT table) -- and department name (DEPTNAME) -- of all employees who were born (BIRTHDATE) earlier than 1930 SELECT EMPNO, LASTNAME, WORKDEPT, DEPTNAME FROM SAMP.EMPLOYEE LEFT OUTER JOIN SAMP.DEPARTMENT ON WORKDEPT = DEPTNO AND YEAR(BIRTHDATE) < 1930 -- List every department with the employee number and -- last name of the manager, -- including departments without a manager SELECT DEPTNO, DEPTNAME, EMPNO, LASTNAME FROM DEPARTMENT LEFT OUTER JOIN EMPLOYEE ON MGRNO = EMPNO
RIGHT OUTER JOIN operation
A RIGHT OUTER JOIN is one of the JOIN operations that allow you to specify a JOIN clause. It preserves the unmatched rows from the second (right) table, joining them with a NULL in the shape of the first (left) table. A LEFT OUTER JOIN B is equivalent to B RIGHT OUTER JOIN A, with the columns in a different order.
Syntax
TableExpression RIGHT [ OUTER ] JOIN TableExpression { ON booleanExpression }
The scope of expressions in the ON clause includes the current tables and any tables in query blocks outer to the current SELECT. The ON clause can reference tables not being joined and does not have to reference either of the tables being joined (though typically it does).
Example 1
-- get all countries and corresponding cities, including -- countries without any cities SELECT COUNTRIES.COUNTRY, CITIES.CITY_NAME FROM CITIES RIGHT OUTER JOIN COUNTRIES ON CITIES.COUNTRY_ISO_CODE = COUNTRIES.COUNTRY_ISO_CODE -- get all countries in Africa and corresponding cities, including -- countries without any cities SELECT COUNTRIES.COUNTRY, CITIES.CITY_NAME FROM CITIES RIGHT OUTER JOIN COUNTRIES ON CITIES.COUNTRY_ISO_CODE = COUNTRIES.COUNTRY_ISO_CODE WHERE Countries.region = 'Africa' -- use the synonymous syntax, RIGHT JOIN, to achieve exactly -- the same results as in the example above SELECT COUNTRIES.COUNTRY, CITIES.CITY_NAME FROM CITIES RIGHT JOIN COUNTRIES ON CITIES.COUNTRY_ISO_CODE = COUNTRIES.COUNTRY_ISO_CODE WHERE Countries.region = 'Africa'
Example 2
-- a TableExpression can be a joinOperation. Therefore -- you can have multiple join operations in a FROM clause -- List every employee number and last name -- with the employee number and last name of their manager SELECT E.EMPNO, E.LASTNAME, M.EMPNO, M.LASTNAME FROM EMPLOYEE E RIGHT OUTER JOIN DEPARTMENT RIGHT OUTER JOIN EMPLOYEE M ON MGRNO = M.EMPNO ON E.WORKDEPT = DEPTNO
SQL queries
Query
A query creates a virtual table based on existing tables or constants built into tables.
Syntax
{ ( Query ) | Query INTERSECT [ ALL | DISTINCT ] Query | Query EXCEPT [ ALL | DISTINCT ] Query | Query UNION [ ALL | DISTINCT ] Query | SelectExpression | VALUES Expression }
You can arbitrarily put parentheses around queries, or use the parentheses to control the order of evaluation of the INTERSECT, EXCEPT, or UNION operations. These operations are evaluated from left to right when no parentheses are present, with the exception of INTERSECT operations, which would be evaluated before any UNION or EXCEPT operations.
Duplicates in UNION, INTERSECT, and EXCEPT ALL results
The ALL and DISTINCT keywords determine whether duplicates are eliminated from the result of the operation. If you specify the DISTINCT keyword, then the result will have no duplicate rows. If you specify the ALL keyword, then there may be duplicates in the result, depending on whether there were duplicates in the input. DISTINCT is the default, so if you don't specify ALL or DISTINCT, the duplicates will be eliminated. For example, UNION builds an intermediate ResultSet with all of the rows from both queries and eliminates the duplicate rows before returning the remaining rows. UNION ALL returns all rows from both queries as the result.
Depending on which operation is specified, if the number of copies of a row in the left table is L and the number of copies of that row in the right table is R, then the number of duplicates of that particular row that the output table contains (assuming the ALL keyword is specified) is:
 
UNION: ( L + R ).
 
EXCEPT: the maximum of ( L – R ) and 0 (zero).
 
INTERSECT: the minimum of L and R.
Examples
-- a Select expression SELECT * FROM ORG -- a subquery SELECT * FROM (SELECT CLASS_CODE FROM CL_SCHED) AS CS -- a subquery SELECT * FROM (SELECT CLASS_CODE FROM CL_SCHED) AS CS (CLASS_CODE) -- a UNION -- returns all rows from columns DEPTNUMB and MANAGER -- in table ORG -- and (1,2) and (3,4) -- DEPTNUMB and MANAGER are smallint columns SELECT DEPTNUMB, MANAGER FROM ORG UNION ALL VALUES (1,2), (3,4) -- a values expression VALUES (1,2,3) -- List the employee numbers (EMPNO) of all employees in the EMPLOYEE table -- whose department number (WORKDEPT) either begins with 'E' or -- who are assigned to projects in the EMP_ACT table -- whose project number (PROJNO) equals 'MA2100', 'MA2110', or 'MA2112' SELECT EMPNO FROM EMPLOYEE WHERE WORKDEPT LIKE 'E%' UNION SELECT EMPNO FROM EMP_ACT WHERE PROJNO IN('MA2100', 'MA2110', 'MA2112') -- Make the same query as in the previous example -- and "tag" the rows from the EMPLOYEE table with 'emp' and -- the rows from the EMP_ACT table with 'emp_act'. -- Unlike the result from the previous example, -- this query may return the same EMPNO more than once, -- identifying which table it came from by the associated "tag" SELECT EMPNO, 'emp' FROM EMPLOYEE WHERE WORKDEPT LIKE 'E%' UNION SELECT EMPNO, 'emp_act' FROM EMP_ACT WHERE PROJNO IN('MA2100', 'MA2110', 'MA2112') -- Make the same query as in the previous example, -- only use UNION ALL so that no duplicate rows are eliminated SELECT EMPNO FROM EMPLOYEE WHERE WORKDEPT LIKE 'E%' UNION ALL SELECT EMPNO FROM EMP_ACT WHERE PROJNO IN('MA2100', 'MA2110', 'MA2112') -- Make the same query as in the previous example, -- only include an additional two employees currently not in any table and -- tag these rows as "new" SELECT EMPNO, 'emp' FROM EMPLOYEE WHERE WORKDEPT LIKE 'E%' UNION SELECT EMPNO, 'emp_act' FROM EMP_ACT WHERE PROJNO IN('MA2100', 'MA2110', 'MA2112') UNION VALUES ('NEWAAA', 'new'), ('NEWBBB', 'new')
ScalarSubquery
You can place a ScalarSubquery anywhere an Expression is permitted. A ScalarSubquery turns a SelectExpression result into a scalar value because it returns only a single row and column value.
The query must evaluate to a single row with a single column.
Sometimes also called an expression subquery.
Syntax
Examples
-- avg always returns a single value, so the subquery is -- a ScalarSubquery SELECT NAME, COMM FROM STAFF WHERE EXISTS (SELECT AVG(BONUS + 800) FROM EMPLOYEE WHERE COMM < 5000 AND EMPLOYEE.LASTNAME = UPPER(STAFF.NAME) ) -- Introduce a way of "generating" new data values, -- using a query which selects from a VALUES clause (which is an -- alternate form of a fullselect). -- This query shows how a table can be derived called "X" having -- 2 columns "R1" and "R2" and 1 row of data. SELECT R1,R2 FROM (VALUES('GROUP 1','GROUP 2')) AS X(R1,R2)
TableSubquery
A TableSubquery is a subquery that returns multiple rows.
Unlike a ScalarSubquery, a TableSubquery is allowed only:
 
 
with EXISTS, IN, or quantified comparisons.
When used as a TableExpression in a FROM clause, it can return multiple columns. When used with EXISTS, it returns multiple columns only if you use * to return the multiple columns.
When used with IN or quantified comparisons, it must return a single column.
Syntax
Example
-- a subquery used as a TableExpression in a FROM clause SELECT VirtualFlightTable.flight_ID FROM (SELECT flight_ID, orig_airport, dest_airport FROM Flights WHERE (orig_airport = 'SFO' OR dest_airport = 'SCL') ) AS VirtualFlightTable -- a subquery (values expression) used as a TableExpression -- in a FROM clause SELECT mycol1 FROM (VALUES (1, 2), (3, 4)) AS mytable (mycol1, mycol2) -- a subquery used with EXISTS SELECT * FROM Flights WHERE EXISTS (SELECT * FROM Flights WHERE dest_airport = 'SFO' AND orig_airport = 'GRU') -- a subquery used with IN SELECT flight_id, segment_number FROM Flights WHERE flight_id IN (SELECT flight_ID FROM Flights WHERE orig_airport = 'SFO' OR dest_airport = 'SCL') -- a subquery used with a quantified comparison SELECT NAME, COMM FROM STAFF WHERE COMM > (SELECT AVG(BONUS + 800) FROM EMPLOYEE WHERE COMM < 5000)
Built-in functions
A built-in function is an expression in which an SQL keyword or special operator executes some operation. Built-in functions use keywords or special built-in operators. Built-ins are SQL92Identifiers and are case-insensitive. Note that escaped functions like TIMESTAMPADD and TIMESTAMPDIFF are only accessible using the JDBC escape function syntax, and can be found in JDBC escape syntax.
Standard built-in functions
The standard built-in functions supported in Derby are as follows:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Aggregates (set functions)
This section describes aggregates (also described as set functions in ANSI SQL-92 and as column functions in some database literature). They provide a means of evaluating an expression over a set of rows. Whereas the other built-in functions operate on a single expression, aggregates operate on a set of values and reduce them to a single scalar value. Built-in aggregates can calculate the minimum, maximum, sum, count, and average of an expression over a set of values as well as count rows.
The built-in aggregates can operate on the data types shown in Permitted Data Types for Built-in Aggregates.
Table 7. Permitted Data Types for Built-in Aggregates
Function Name
All Types
Numeric Built-in Data Types
COUNT
X
X
MIN
 
X
MAX
 
X
AVG
 
X
SUM
 
X
Aggregates are permitted only in the following:
 
A SelectItem in a SelectExpression.
 
 
An ORDER BY clause (using an alias name) if the aggregate appears in the result of the relevant query block. That is, an alias for an aggregate is permitted in an ORDER BY clause if and only if the aggregate appears in a SelectItem in a SelectExpression.
All expressions in SelectItems in the SelectExpression must be either aggregates or grouped columns (see GROUP BY clause). (The same is true if there is a HAVING clause without a GROUP BY clause.) This is because the ResultSet of a SelectExpression must be either a scalar (single value) or a vector (multiple values), but not a mixture of both. (Aggregates evaluate to a scalar value, and the reference to a column can evaluate to a vector.) For example, the following query mixes scalar and vector values and thus is not valid:
-- not valid SELECT MIN(flying_time), flight_id FROM Flights
Aggregates are not allowed on outer references (correlations). This means that if a subquery contains an aggregate, that aggregate cannot evaluate an expression that includes a reference to a column in the outer query block. For example, the following query is not valid because SUM operates on a column from the outer query:
SELECT c1 FROM t1 GROUP BY c1 HAVING c2 > (SELECT t2.x FROM t2 WHERE t2.y = SUM(t1.c3))
A cursor declared on a ResultSet that includes an aggregate in the outer query block is not updatable.
Derby supports the following aggregates:
ABS or ABSVAL function
ABS or ABSVAL returns the absolute value of a numeric expression. The return type is the type of parameter. All built-in numeric types are supported (DECIMAL, DOUBLE PRECISION, FLOAT, INTEGER, BIGINT, NUMERIC, REAL, and SMALLINT).
Syntax
ABS(NumericExpression)
-- returns 3 VALUES ABS(-3)
ACOS function
The ACOS function returns the arc cosine of a specified number.
The specified number is the cosine, in radians, of the angle that you want. The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of this function is NULL.
 
If the absolute value of the specified number is greater than 1, an exception is returned that indicates that the value is out of range (SQL state 22003).
The returned value, in radians, is in the range of zero (0) to pi. The data type of the returned value is a DOUBLE PRECISION number.
Syntax
ACOS ( number )
ASIN function
The ASIN function returns the arc sine of a specified number.
The specified number is the sine, in radians, of the angle that you want. The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of this function is NULL.
 
If the specified number is zero (0), the result of this function is zero with the same sign as the specified number.
 
If the absolute value of the specified number is greater than 1, an exception is returned that indicates that the value is out of range (SQL state 22003).
The returned value, in radians, is in the range -pi/2 to pi/2. The data type of the returned value is a DOUBLE PRECISION number.
Syntax
ASIN ( number )
ATAN function
The ATAN function returns the arc tangent of a specified number.
The specified number is the tangent, in radians, of the angle that you want. The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of this function is NULL.
 
If the specified number is zero (0), the result of this function is zero with the same sign as the specified number.
The returned value, in radians, is in the range -pi/2 to pi/2. The data type of the returned value is a DOUBLE PRECISION number.
Syntax
ATAN ( number )
ATAN2 function
The ATAN2 function returns the arctangent, in radians, of the quotient of the two arguments.
Upon successful completion, the function returns the arc tangent of y/x in the range -pi to pi radians, where y is the first argument and x is the second argument. The specified numbers must be DOUBLE PRECISION numbers.
 
If either argument is NULL, the result of the function is NULL.
 
If the first argument is zero and the second argument is positive, the result of the function is zero.
 
If the first argument is zero and the second argument is negative, the result of the function is the double value closest to pi.
 
If the first argument is positive and the second argument is zero, the result is the double value closest to pi/2.
 
If the first argument is negative and the second argument is zero, the result is the double value closest to -pi/2.
The data type of the returned value is a DOUBLE PRECISION number.
Syntax
ATAN2 ( y, x )
AVG function
AVG is an aggregate function that evaluates the average of an expression over a set of rows (see Aggregates (set functions)). AVG is allowed only on expressions that evaluate to numeric data types.
Syntax
AVG ( [ DISTINCT | ALL ] Expression )
The DISTINCT qualifier eliminates duplicates. The ALL qualifier retains duplicates. ALL is the default value if neither ALL nor DISTINCT is specified. For example, if a column contains the values 1.0, 1.0, 1.0, 1.0, and 2.0, AVG(col) returns a smaller value than AVG(DISTINCT col).
Only one DISTINCT aggregate expression per SelectExpression is allowed. For example, the following query is not valid:
SELECT AVG (DISTINCT flying_time), SUM (DISTINCT miles) FROM Flights
The expression can contain multiple column references or expressions, but it cannot contain another aggregate or subquery. It must evaluate to an SQL-92 numeric data type. You can therefore call methods that evaluate to SQL-92 data types. If an expression evaluates to NULL, the aggregate skips that value.
The resulting data type is the same as the expression on which it operates (it will never overflow). The following query, for example, returns the INTEGER 1, which might not be what you would expect:
SELECT AVG(c1) FROM (VALUES (1), (1), (1), (1), (2)) AS myTable (c1)
CAST the expression to another data type if you want more precision:
SELECT AVG(CAST (c1 AS DOUBLE PRECISION)) FROM (VALUES (1), (1), (1), (1), (2)) AS myTable (c1)
BIGINT function
The BIGINT function returns a 64-bit integer representation of a number or character string in the form of an integer constant.
Syntax
BIGINT (CharacterExpression | NumericExpression )
CharacterExpression
An expression that returns a character string value of length not greater than the maximum length of a character constant. Leading and trailing blanks are eliminated and the resulting string must conform to the rules for forming an SQL integer constant. The character string cannot be a long string. If the argument is a CharacterExpression, the result is the same number that would occur if the corresponding integer constant were assigned to a big integer column or variable.
NumericExpression
An expression that returns a value of any built-in numeric data type. If the argument is a NumericExpression, the result is the same number that would occur if the argument were assigned to a big integer column or variable. If the whole part of the argument is not within the range of integers, an error occurs. The decimal part of the argument is truncated if present.
The result of the function is a big integer. If the argument can be null, the result can be null; if the argument is null, the result is the null value.
Using the EMPLOYEE table, select the EMPNO column in big integer form for further processing in the application:
SELECT BIGINT (EMPNO) FROM EMPLOYEE
CASE expressions
Use the CASE expressions for conditional expressions in Derby.
CASE expression syntax
You can place a CASE expression anywhere an expression is allowed. It chooses an expression to evaluate based on a boolean test.
CASE WHEN booleanExpression THEN thenExpression [ WHEN booleanExpression THEN thenExpression ]... ELSE elseExpression END
ThenExpression and elseExpression are both expressions that must be type-compatible. For built-in types, this means that the types must be the same or a built-in broadening conversion must exist between the types.
-- returns 3 VALUES CASE WHEN 1=1 THEN 3 ELSE 4 END
-- returns 7 VALUES CASE WHEN 1 = 2 THEN 3 WHEN 4 = 5 THEN 6 ELSE 7 END
CAST function
The CAST function converts a value from one data type to another and provides a data type to a dynamic parameter (?) or a NULL value.
CAST expressions are permitted anywhere expressions are permitted.
Syntax
CAST ( [ Expression | NULL | ? ] AS Datatype)
The data type to which you are casting an expression is the target type. The data type of the expression from which you are casting is the source type.
CAST conversions among SQL-92 data types
The following table shows valid explicit conversions between source types and target types for SQL data types. This table shows which explicit conversions between data types are valid. The first column on the table lists the source data types. The first row lists the target data types. A "Y" indicates that a conversion from the source to the target is valid. For example, the first cell in the second row lists the source data type SMALLINT. The remaining cells on the second row indicate the whether or not you can convert SMALLINT to the target data types that are listed in the first row of the table.
Table 8. Explicit conversions between source types and target types for SQL data types
Types
S M A L L I N T
I N T E G E R
B I G I N T
D E C I M A L
R E A L
D O U B L E
F L O A T
C H A R
V A R C H A R
L O N G V A R C H A R
C H A R F O R B I T D A T A
V A R C H A R F O R B I T D A T A
L O N G V A R C H A R F O R B I T D A T A
C L O B
B L O B
D A T E
T I M E
T I M E S T A M P
X M L
SMALLINT
Y
Y
Y
Y
Y
Y
Y
Y
-
-
-
-
-
-
-
-
-
-
-
INTEGER
Y
Y
Y
Y
Y
Y
Y
Y
-
-
-
-
-
-
-
-
-
-
-
BIGINT
Y
Y
Y
Y
Y
Y
Y
Y
-
-
-
-
-
-
-
-
-
-
-
DECIMAL
Y
Y
Y
Y
Y
Y
Y
Y
-
-
-
-
-
-
-
-
-
-
-
REAL
Y
Y
Y
Y
Y
Y
Y
-
-
-
-
-
-
-
-
-
-
-
-
DOUBLE
Y
Y
Y
Y
Y
Y
Y
-
-
-
-
-
-
-
-
-
-
-
-
FLOAT
Y
Y
Y
Y
Y
Y
Y
-
-
-
-
-
-
-
-
-
-
-
-
CHAR
Y
Y
Y
Y
-
-
-
Y
Y
Y
-
-
-
Y
-
Y
Y
Y
-
VARCHAR
Y
Y
Y
Y
-
-
-
Y
Y
Y
-
-
-
Y
-
Y
Y
Y
-
LONG VARCHAR
-
-
-
-
-
-
-
Y
Y
Y
-
-
-
Y
-
-
-
-
-
CHAR FOR BIT DATA
-
-
-
-
-
-
-
-
-
-
Y
Y
Y
Y
Y
-
-
-
-
VARCHAR FOR BIT DATA
-
-
-
-
-
-
-
-
-
-
Y
Y
Y
Y
Y
-
-
-
-
LONG VARCHAR FOR BIT DATA
-
-
-
-
-
-
-
-
-
-
Y
Y
Y
Y
Y
-
-
-
-
CLOB
-
-
-
-
-
-
-
Y
Y
Y
-
-
-
Y
-
-
-
-
-
BLOB
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Y
-
-
-
-
DATE
-
-
-
-
-
-
-
Y
Y
-
-
-
-
-
-
Y
-
-
-
TIME
-
-
-
-
-
-
-
Y
Y
-
-
-
-
-
-
-
Y
-
-
TIMESTAMP
-
-
-
-
-
-
-
Y
Y
-
-
-
-
-
-
Y
Y
Y
-
XML
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Y
If a conversion is valid, CASTs are allowed. Size incompatibilities between the source and target types might cause runtime errors.
Notes
In this discussion, the Derby SQL-92 data types are categorized as follows:
 
numeric
 
Exact numeric (SMALLINT, INTEGER, BIGINT, DECIMAL, NUMERIC)
 
Approximate numeric (FLOAT, REAL, DOUBLE PRECISION)
 
 
date/time
 
 
 
Conversions from numeric types
A numeric type can be converted to any other numeric type. If the target type cannot represent the non-fractional component without truncation, an exception is raised. If the target numeric cannot represent the fractional component (scale) of the source numeric, then the source is silently truncated to fit into the target. For example, casting 763.1234 as INTEGER yields 763.
Conversions from and to bit strings
Bit strings can be converted to other bit strings, but not character strings. Strings that are converted to bit strings are padded with trailing zeros to fit the size of the target bit string. The BLOB type is more limited and requires explicit casting. In most cases the BLOB type cannot be casted to and from other types.
Conversions of date/time values
A date/time value can always be converted to and from a TIMESTAMP. If a DATE is converted to a TIMESTAMP, the TIME component of the resulting TIMESTAMP is always 00:00:00. If a TIME data value is converted to a TIMESTAMP, the DATE component is set to the value of CURRENT_DATE at the time the CAST is executed. If a TIMESTAMP is converted to a DATE, the TIME component is silently truncated. If a TIMESTAMP is converted to a TIME, the DATE component is silently truncated.
SELECT CAST (miles AS INT) FROM Flights -- convert timestamps to text INSERT INTO mytable (text_column) VALUES (CAST (CURRENT_TIMESTAMP AS VARCHAR(100))) -- you must cast NULL as a data type to use it SELECT airline FROM Airlines UNION ALL VALUES (CAST (NULL AS CHAR(2))) -- cast a double as a decimal SELECT CAST (FLYING_TIME AS DECIMAL(5,2)) FROM FLIGHTS -- cast a SMALLINT to a BIGINT VALUES CAST (CAST (12 as SMALLINT) as BIGINT)
Conversions of XML values
An XML value cannot be converted to any non-XML type using an explicit or implicit CAST. Use the XMLSERIALIZE operator to convert an XML type to a character type.
CEIL or CEILING function
The CEIL and CEILING functions round the specified number up, and return the smallest number that is greater than or equal to the specified number.
The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of these functions is NULL.
 
If the specified number is equal to a mathematical integer, the result of these functions is the same as the specified number.
 
If the specified number is zero (0), the result of these functions is zero.
 
If the specified number is less than zero but greater than -1.0, then the result of these functions is zero.
The returned value is the smallest (closest to negative infinity) double floating point value that is greater than or equal to the specified number. The returned value is equal to a mathematical integer. The data type of the returned value is a DOUBLE PRECISION number.
Syntax
CEIL ( number )
CEILING ( number )
CHAR function
The CHAR function returns a fixed-length character string representation.
The representations are:
 
A character string, if the first argument is any type of character string.
 
A datetime value, if the first argument is a date, time, or timestamp.
 
A decimal number, if the first argument is a decimal number.
 
A double-precision floating-point number, if the first argument is a DOUBLE or REAL.
 
An integer number, if the first argument is a SMALLINT, INTEGER, or BIGINT.
The first argument must be of a built-in data type. The result of the CHAR function is a fixed-length character string. If the first argument can be null, the result can be null. If the first argument is null, the result is the null value. The first argument cannot be an XML value. To convert an XML value to a CHAR of a specified length, you must use the SQL/XML serialization operator XMLSERIALIZE.
Character to character syntax
CHAR (CharacterExpression [, integer] )
CharacterExpression
An expression that returns a value that is CHAR, VARCHAR, LONG VARCHAR, or CLOB data type.
integer
The length attribute for the resulting fixed length character string. The value must be between 0 and 254.
If the length of the character-expression is less than the length attribute of the result, the result is padded with blanks up to the length of the result. If the length of the character-expression is greater than the length attribute of the result, truncation is performed. A warning is returned unless the truncated characters were all blanks and the character-expression was not a long string (LONG VARCHAR or CLOB).
Integer to character syntax
CHAR (IntegerExpression )
IntegerExpression
An expression that returns a value that is an integer data type (either SMALLINT, INTEGER or BIGINT).
The result is the character string representation of the argument in the form of an SQL integer constant. The result consists of n characters that are the significant digits that represent the value of the argument with a preceding minus sign if the argument is negative. It is left justified.
 
If the first argument is a small integer: The length of the result is 6. If the number of characters in the result is less than 6, then the result is padded on the right with blanks to length 6.
 
If the first argument is a large integer: The length of the result is 11. If the number of characters in the result is less than 11, then the result is padded on the right with blanks to length 11.
 
If the first argument is a big integer: The length of the result is 20. If the number of characters in the result is less than 20, then the result is padded on the right with blanks to length 20.
Datetime to character syntax
CHAR (DatetimeExpression )
DatetimeExpression
An expression that is one of the following three data types:
 
date: The result is the character representation of the date. The length of the result is 10.
 
time: The result is the character representation of the time. The length of the result is 8.
 
timestamp: The result is the character string representation of the timestamp. The length of the result is 26.
Decimal to character
CHAR (DecimalExpression )
DecimalExpression
An expression that returns a value that is a decimal data type. If a different precision and scale is desired, the DECIMAL scalar function can be used first to make the change.
Floating point to character syntax
CHAR (FloatingPointExpression )
FloatingPointExpression
An expression that returns a value that is a floating-point data type (DOUBLE or REAL).
Use the CHAR function to return the values for EDLEVEL (defined as smallint) as a fixed length character string:
SELECT CHAR(EDLEVEL) FROM EMPLOYEE
An EDLEVEL of 18 would be returned as the CHAR(6) value '18    ' (18 followed by four blanks).
Concatenation operator
The concatenation operator, ||, concatenates its right operand to the end of its left operand. It operates on a character or bit expression.
Because all built-in data types are implicitly converted to strings, this function can act on all built-in data types.
Syntax
{ { CharacterExpression || CharacterExpression } | { BitExpression || BitExpression } }
For character strings, if both the left and right operands are of type CHAR, the resulting type is CHAR; otherwise, it is VARCHAR. The normal blank padding/trimming rules for CHAR and VARCHAR apply to the result of this operator.
The length of the resulting string is the sum of the lengths of both operands.
For bit strings, if both the left and the right operands are of type CHAR FOR BIT DATA, the resulting type is CHAR FOR BIT DATA; otherwise, it is VARCHAR FOR BIT DATA.
--returns 'supercalifragilisticexbealidocious(sp?)' VALUES 'supercalifragilistic' || 'exbealidocious' || '(sp?)' -- returns NULL VALUES CAST (null AS VARCHAR(7))|| 'AString' -- returns '130asdf' VALUES '130' || 'asdf'
COS function
The COS function returns the cosine of a specified number.
The specified number is the angle, in radians, that you want the cosine for. The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of this function is NULL.
Syntax
COS ( number )
COSH function
The COSH function returns the hyperbolic cosine of a specified number.
The specified number is the angle, in radians, that you want the hyperbolic cosine for. The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of this function is NULL.
 
If the specified number is zero (0), the result of this function is one (1.0).
Syntax
COSH ( number )
COT function
The COT function returns the cotangens of a specified number.
The specified number is the angle, in radians, that you want the cotangens for. The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of this function is NULL.
Syntax
COT ( number )
COUNT function
COUNT is an aggregate function that counts the number of rows accessed in an expression (see Aggregates (set functions)). COUNT is allowed on all types of expressions.
Syntax
COUNT ( [ DISTINCT | ALL ] Expression )
The DISTINCT qualifier eliminates duplicates. The ALL qualifier retains duplicates. ALL is assumed if neither ALL nor DISTINCT is specified. For example, if a column contains the values 1, 1, 1, 1, and 2, COUNT(col) returns a greater value than COUNT(DISTINCT col).
Only one DISTINCT aggregate expression per SelectExpression is allowed. For example, the following query is not allowed:
-- query not allowed SELECT COUNT (DISTINCT flying_time), SUM (DISTINCT miles) FROM Flights
An Expression can contain multiple column references or expressions, but it cannot contain another aggregate or subquery. If an Expression evaluates to NULL, the aggregate is not processed for that value.
The resulting data type of COUNT is INTEGER.
-- Count the number of countries in each region, -- show only regions that have at least 2 SELECT COUNT (country), region FROM Countries GROUP BY region HAVING COUNT (country) > 1
COUNT(*) function
COUNT(*) is an aggregate function that counts the number of rows accessed. No NULLs or duplicates are eliminated. COUNT(*) does not operate on an expression.
Syntax
COUNT(*)
The resulting data type is INTEGER.
-- Count the number of rows in the Flights table SELECT COUNT(*) FROM Flights
CURRENT DATE function
CURRENT DATE is a synonym for CURRENT_DATE.
CURRENT_DATE function
CURRENT_DATE returns the current date; the value returned does not change if it is executed more than once in a single statement. This means the value is fixed even if there is a long delay between fetching rows in a cursor.
Syntax
CURRENT_DATE
or, alternately
CURRENT DATE
-- find available future flights: SELECT * FROM Flightavailability where flight_date > CURRENT_DATE;
CURRENT ISOLATION function
CURRENT ISOLATION returns the current isolation level as a char(2) value of either ""(blank), "UR", "CS", "RS", or "RR".
Syntax
CURRENT ISOLATION
VALUES CURRENT ISOLATION
CURRENT_ROLE function
CURRENT_ROLE returns the authorization identifier of the current role. If there is no current role, it returns NULL.
This function returns a string of up to 258 characters. This is twice the length of an identifier (128*2) + 2, to allow for quoting.
Syntax
CURRENT_ROLE
Example
VALUES CURRENT_ROLE
CURRENT SCHEMA function
CURRENT SCHEMA returns the schema name used to qualify unqualified database object references.
Note: CURRENT SCHEMA and CURRENT SQLID are synonyms.
These functions return a string of up to 128 characters.
Syntax
CURRENT SCHEMA -- or, alternately: CURRENT SQLID
-- Set the name column default to the current schema: CREATE TABLE mytable (id int, name VARCHAR(128) DEFAULT CURRENT SQLID) -- Inserts default value of current schema value into the table: INSERT INTO mytable(id) VALUES (1) -- Returns the rows with the same name as the current schema: SELECT name FROM mytable WHERE name = CURRENT SCHEMA
CURRENT TIME function
CURRENT TIME is a synonym for CURRENT_TIME.
CURRENT_TIME function
CURRENT_TIME returns the current time; the value returned does not change if it is executed more than once in a single statement. This means the value is fixed even if there is a long delay between fetching rows in a cursor.
Syntax
CURRENT_TIME
or, alternately
CURRENT TIME
VALUES CURRENT_TIME -- or, alternately: VALUES CURRENT TIME
CURRENT TIMESTAMP function
CURRENT TIMESTAMP is a synonym for CURRENT_TIMESTAMP.
CURRENT_TIMESTAMP function
CURRENT_TIMESTAMP returns the current timestamp; the value returned does not change if it is executed more than once in a single statement. This means the value is fixed even if there is a long delay between fetching rows in a cursor.
Syntax
CURRENT_TIMESTAMP
or, alternately
CURRENT TIMESTAMP
VALUES CURRENT_TIMESTAMP -- or, alternately: VALUES CURRENT TIMESTAMP
CURRENT_USER function
CURRENT_USER returns the authorization identifier of the current user (the name of the user passed in when the user connected to the database). If there is no current user, it returns APP.
USER and SESSION_USER are synonyms.
These functions return a string of up to 128 characters.
Syntax
CURRENT_USER
VALUES CURRENT_USER
DATE function
The DATE function returns a date from a value.
The argument must be a date, timestamp, a positive number less than or equal to 2,932,897, a valid string representation of a date or timestamp, or a string of length 7 that is not a CLOB, LONG VARCHAR, or XML value. If the argument is a string of length 7, it must represent a valid date in the form yyyynnn, where yyyy are digits denoting a year, and nnn are digits between 001 and 366, denoting a day of that year. The result of the function is a date. If the argument can be null, the result can be null; if the argument is null, the result is the null value.
The other rules depend on the data type of the argument specified:
 
If the argument is a date, timestamp, or valid string representation of a date or timestamp: The result is the date part of the value.
 
If the argument is a number: The result is the date that is n-1 days after January 1, 0001, where n is the integral part of the number.
 
If the argument is a string with a length of 7: The result is the date represented by the string.
Syntax
DATE ( expression )
This example results in an internal representation of '1988-12-25'.
VALUES DATE('1988-12-25')
DAY function
The DAY function returns the day part of a value.
The argument must be a date, timestamp, or a valid character string representation of a date or timestamp that is not a CLOB, LONG VARCHAR, or XML value. The result of the function is an integer between 1 and 31. If the argument can be null, the result can be null; if the argument is null, the result is the null value.
Syntax
DAY ( expression )
Example
values day('2007-08-02');
The resulting value is 2.
DEGREES function
The DEGREES function converts a specified number from radians to degrees.
The specified number is an angle measured in radians, which is converted to an approximately equivalent angle measured in degrees. The specified number must be a DOUBLE PRECISION number.
Attention: The conversion from radians to degrees is not exact. You should not expect DEGREES(ACOS(0.5)) to return exactly 60.0.
The data type of the returned value is a DOUBLE PRECISION number.
Syntax
DEGREES ( number )
DOUBLE function
The DOUBLE function returns a floating-point number corresponding to a:
 
number if the argument is a numeric expression.
 
character string representation of a number if the argument is a string expression.
Numeric to double
DOUBLE [PRECISION] (NumericExpression )
NumericExpression
The argument is an expression that returns a value of any built-in numeric data type.
The result of the function is a double-precision floating-point number. If the argument can be null, the result can be null; if the argument is null, the result is the null value. The result is the same number that would occur if the argument were assigned to a double-precision floating-point column or variable.
Character string to double
DOUBLE (StringExpression )
StringExpression
The argument can be of type CHAR or VARCHAR in the form of a numeric constant. Leading and trailing blanks in argument are ignored.
The result of the function is a double-precision floating-point number. The result can be null; if the argument is null, the result is the null value. The result is the same number that would occur if the string was considered a constant and assigned to a double-precision floating-point column or variable.
EXP function
The EXP function returns e raised to the power of the specified number.
The specified number is the exponent that you want to raise e to. The specified number must be a DOUBLE PRECISION number.
The constant e is the base of the natural logarithms.
The data type of the returned value is a DOUBLE PRECISION number.
Syntax
EXP ( number )
FLOOR function
The FLOOR function rounds the specified number down, and returns the largest number that is less than or equal to the specified number.
The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of this function is NULL.
 
If the specified number is equal to a mathematical integer, the result of this function is the same as the specified number.
 
If the specified number is zero (0), the result of this function is zero.
The returned value is the largest (closest to positive infinity) double floating point value that is less than or equal to the specified number. The returned value is equal to a mathematical integer. The data type of the returned value is a DOUBLE PRECISION number.
Syntax
FLOOR ( number )
HOUR function
The HOUR function returns the hour part of a value.
The argument must be a time, timestamp, or a valid character string representation of a time or timestamp that is not a CLOB, LONG VARCHAR, or XML value. The result of the function is an integer between 0 and 24. If the argument can be null, the result can be null; if the argument is null, the result is the null value.
Syntax
HOUR ( expression )
Example
Select all the classes that start in the afternoon from a table called TABLE1.
SELECT * FROM TABLE1 WHERE HOUR(STARTING) BETWEEN 12 AND 17
IDENTITY_VAL_LOCAL function
Derby supports the IDENTITY_VAL_LOCAL function.
Syntax:
IDENTITY_VAL_LOCAL ( )
The IDENTITY_VAL_LOCAL function is a non-deterministic function that returns the most recently assigned value of an identity column for a connection, where the assignment occurred as a result of a single row INSERT statement using a VALUES clause.
The IDENTITY_VAL_LOCAL function has no input parameters. The result is a DECIMAL (31,0), regardless of the actual data type of the corresponding identity column.
The value returned by the IDENTITY_VAL_LOCAL function, for a connection, is the value assigned to the identity column of the table identified in the most recent single row INSERT statement. The INSERT statement must contain a VALUES clause on a table containing an identity column. The assigned value is an identity value generated by Derby. The function returns a null value when a single row INSERT statement with a VALUES clause has not been issued for a table containing an identity column.
The result of the function is not affected by the following:
 
A single row INSERT statement with a VALUES clause for a table without an identity column
 
A multiple row INSERT statement with a VALUES clause
 
An INSERT statement with a fullselect
If a table with an identity column has an INSERT trigger defined that inserts into another table with another identity column, then the IDENTITY_VAL_LOCAL() function will return the generated value for the statement table, and not for the table modified by the trigger.
Examples:
ij> create table t1(c1 int generated always as identity, c2 int); 0 rows inserted/updated/deleted ij> insert into t1(c2) values (8); 1 row inserted/updated/deleted ij> values IDENTITY_VAL_LOCAL(); 1 ------------------------------- 1 1 row selected ij> select IDENTITY_VAL_LOCAL()+1, IDENTITY_VAL_LOCAL()-1 from t1; 1 |2 ------------------------------------------------------------------- 2 |0 1 row selected ij> insert into t1(c2) values (IDENTITY_VAL_LOCAL()); 1 row inserted/updated/deleted ij> select * from t1; C1 |C2 ------------------------------- 1 |8 2 |1 2 rows selected ij> values IDENTITY_VAL_LOCAL(); 1 ------------------------------- 2 1 row selected ij> insert into t1(c2) values (8), (9); 2 rows inserted/updated/deleted ij> -- multi-values insert, return value of the function should not change values IDENTITY_VAL_LOCAL(); 1 ------------------------------- 2 1 row selected ij> select * from t1; C1 |C2 ------------------------------- 1 |8 2 |1 3 |8 4 |9 4 rows selected ij> insert into t1(c2) select c1 from t1; 4 rows inserted/updated/deleted -- insert with sub-select, return value should not change ij> values IDENTITY_VAL_LOCAL(); 1 ------------------------------- 2 1 row selected ij> select * from t1; C1 |C2 ------------------------------- 1 |8 2 |1 3 |8 4 |9 5 |1 6 |2 7 |3 8 |4 8 rows selected
INTEGER function
The INTEGER function returns an integer representation of a number, character string, date, or time in the form of an integer constant.
Syntax
INT[EGER] (NumericExpression | CharacterExpression )
NumericExpression
An expression that returns a value of any built-in numeric data type. If the argument is a numeric-expression, the result is the same number that would occur if the argument were assigned to a large integer column or variable. If the whole part of the argument is not within the range of integers, an error occurs. The decimal part of the argument is truncated if present.
CharacterExpression
An expression that returns a character string value of length not greater than the maximum length of a character constant. Leading and trailing blanks are eliminated and the resulting string must conform to the rules for forming an SQL integer constant. The character string cannot be a long string. If the argument is a character-expression, the result is the same number that would occur if the corresponding integer constant were assigned to a large integer column or variable.
The result of the function is a large integer. If the argument can be null, the result can be null; if the argument is null, the result is the null value.
Using the EMPLOYEE table, select a list containing salary (SALARY) divided by education level (EDLEVEL). Truncate any decimal in the calculation. The list should also contain the values used in the calculation and employee number (EMPNO). The list should be in descending order of the calculated value:
SELECT INTEGER (SALARY / EDLEVEL), SALARY, EDLEVEL, EMPNO FROM EMPLOYEE ORDER BY 1 DESC
LCASE or LOWER function
LCASE or LOWER takes a character expression as a parameter and returns a string in which all alpha characters have been converted to lowercase.
Syntax
LCASE or LOWER ( CharacterExpression )
A CharacterExpression is a CHAR, VARCHAR, or LONG VARCHAR data type or any built-in type that is implicitly converted to a string (except a bit expression).
If the parameter type is CHAR or LONG VARCHAR, the return type is CHAR or LONG VARCHAR. Otherwise, the return type is VARCHAR.
The length and maximum length of the returned value are the same as the length and maximum length of the parameter.
If the CharacterExpression evaluates to null, this function returns null.
-- returns 'asd1#w' VALUES LOWER('aSD1#w') SELECT LOWER(flight_id) FROM Flights
LENGTH function
LENGTH is applied to either a character string expression or a bit string expression and returns the number of characters in the result.
Because all built-in data types are implicitly converted to strings, this function can act on all built-in data types.
Syntax
LENGTH ( { CharacterExpression | BitExpression } )
-- returns 20 VALUES LENGTH('supercalifragilistic') -- returns 1 VALUES LENGTH(X'FF') -- returns 4 VALUES LENGTH(1234567890)
LN or LOG function
The LN and LOG functions return the natural logarithm (base e) of the specified number.
The specified number must be a DOUBLE PRECISION number that is greater than zero (0).
 
If the specified number is NULL, the result of these functions is NULL.
 
If the specified number is zero or a negative number, an exception is returned that indicates that the value is out of range (SQL state 22003).
The data type of the returned value is a DOUBLE PRECISION number.
Syntax
LN ( number )
LOG ( number )
LOG10 function
The LOG10 function returns the base-10 logarithm of the specified number.
The specified number must be a DOUBLE PRECISION number that is greater than zero (0).
 
If the specified number is NULL, the result of this function is NULL.
 
If the specified number is zero or a negative number, an exception is returned that indicates that the value is out of range (SQL state 22003).
The data type of the returned value is a DOUBLE PRECISION number.
Syntax
LOG10 ( number )
LOCATE function
The LOCATE function is used to search for a string within another string. If the desired string is found, LOCATE returns the index at which it is found. If the desired string is not found, LOCATE returns 0.
Syntax
LOCATE(CharacterExpression, CharacterExpression [, StartPosition] )
There are two required arguments to the LOCATE function, and a third optional argument.
 
The first CharacterExpression specifies the string to search for.
 
The second CharacterExpression specifies the string in which to search.
 
The third argument is the startPosition, and specifies the position in the second argument at which the search is to start. If the third argument is not provided, the LOCATE function starts its search at the beginning of the second argument.
The return type for LOCATE is an integer. The LOCATE function returns an integer indicating the index position within the second argument at which the first argument was first located. Index positions start with 1. If the first argument is not found in the second argument, LOCATE returns 0. If the first argument is an empty string (''), LOCATE returns the value of the third argument (or 1 if it was not provided), even if the second argument is also an empty string. If a NULL value is passed for either of the CharacterExpression arguments, NULL is returned.
-- returns 2, since 'love' is found at index position 2: VALUES LOCATE('love', 'clover')
-- returns 0, since 'stove' is not found in 'clover': VALUES LOCATE('stove', 'clover')
-- returns 5 (note the start position is 4): VALUES LOCATE('iss', 'Mississippi', 4)
-- returns 1, because the empty string is a special case: VALUES LOCATE('', 'ABC')
-- returns 0, because 'AAA' is not found in '': VALUES LOCATE('AAA', '')
-- returns 3 VALUES LOCATE('', '', 3)
LTRIM function
LTRIM removes blanks from the beginning of a character string expression.
Syntax
LTRIM(CharacterExpression)
A CharacterExpression is a CHAR, VARCHAR, or LONG VARCHAR data type, any built-in type that is implicitly converted to a string.
LTRIM returns NULL if CharacterExpression evaluates to null.
-- returns 'asdf ' VALUES LTRIM(' asdf ')
MAX function
MAX is an aggregate function that evaluates the maximum of an expression over a set of rows (see Aggregates (set functions)). MAX is allowed only on expressions that evaluate to built-in data types (including CHAR, VARCHAR, DATE, TIME, CHAR FOR BIT DATA, etc.).
Syntax
MAX ( [ DISTINCT | ALL ] Expression )
The DISTINCT and ALL qualifiers eliminate or retain duplicates, but these qualifiers have no effect in a MAX expression. Only one DISTINCT aggregate expression per SelectExpression is allowed. For example, the following query is not allowed:
SELECT COUNT (DISTINCT flying_time), MAX (DISTINCT miles) FROM Flights
The Expression can contain multiple column references or expressions, but it cannot contain another aggregate or subquery. It must evaluate to a built-in data type. You can therefore call methods that evaluate to built-in data types. (For example, a method that returns a java.lang.Integer or int evaluates to an INTEGER.) If an expression evaluates to NULL, the aggregate skips that value.
The type's comparison rules determine the maximum value. For CHAR and VARCHAR, the number of blank spaces at the end of the value can affect how MAX is evaluated. For example, if the values 'z' and 'z ' are both stored in a column, you cannot control which one will be returned as the maximum, because blank spaces are ignored for character comparisons.
The resulting data type is the same as the expression on which it operates (it will never overflow).
-- find the latest date in the FlightAvailability table SELECT MAX (flight_date) FROM FlightAvailability -- find the longest flight originating from each airport, -- but only when the longest flight is over 10 hours SELECT MAX(flying_time), orig_airport FROM Flights GROUP BY orig_airport HAVING MAX(flying_time) > 10
MIN function
MIN is an aggregate function that evaluates the minimum of an expression over a set of rows (see Aggregates (set functions)). MIN is allowed only on expressions that evaluate to built-in data types (including CHAR, VARCHAR, DATE, TIME, etc.).
Syntax
MIN ( [ DISTINCT | ALL ] Expression )
The DISTINCT and ALL qualifiers eliminate or retain duplicates, but these qualifiers have no effect in a MIN expression. Only one DISTINCT aggregate expression per SelectExpression is allowed. For example, the following query is not allowed:
SELECT COUNT (DISTINCT flying_time), MIN (DISTINCT miles) FROM Flights
The Expression can contain multiple column references or expressions, but it cannot contain another aggregate or subquery. It must evaluate to a built-in data type. You can therefore call methods that evaluate to built-in data types. (For example, a method that returns a java.lang.Integer or int evaluates to an INTEGER.) If an expression evaluates to NULL, the aggregate skips that value.
The type's comparison rules determine the minimum value. For CHAR and VARCHAR, the number of blank spaces at the end of the value can affect how MIN is evaluated. For example, if the values 'z' and 'z ' are both stored in a column, you cannot control which one will be returned as the minimum, because blank spaces are ignored for character comparisons.
The resulting data type is the same as the expression on which it operates (it will never overflow).
-- NOT valid: SELECT DISTINCT flying_time, MIN(DISTINCT miles) from Flights -- valid: SELECT COUNT(DISTINCT flying_time), MIN(DISTINCT miles) from Flights -- find the earliest date: SELECT MIN (flight_date) FROM FlightAvailability;
MINUTE function
The MINUTE function returns the minute part of a value.
The argument must be a time, timestamp, or a valid character string representation of a time or timestamp that is not a CLOB, LONG VARCHAR, or XML value. The result of the function is an integer between 0 and 59. If the argument can be null, the result can be null; if the argument is null, the result is the null value.
Syntax
MINUTE ( expression )
Example
Select all rows from the "flights" table where the "departure_time" is between 6:00 and 6:30 AM:
SELECT * FROM flights WHERE HOUR(departure_time) = 6 and MINUTE(departure_time) < 31;
MOD function
MOD returns the remainder (modulus) of argument 1 divided by argument 2. The result is negative only if argument 1 is negative.
Syntax
mod(integer_type, integer_type)
The result of the function is:
 
SMALLINT if both arguments are SMALLINT.
 
INTEGER if one argument is INTEGER and the other is INTEGER or SMALLINT.
 
BIGINT if one integer is BIGINT and the other argument is BIGINT, INTEGER, or SMALLINT.
The result can be null; if any argument is null, the result is the null value.
MONTH function
The MONTH function returns the month part of a value.
The argument must be a date, timestamp, or a valid character string representation of a date or timestamp that is not a CLOB, LONG VARCHAR, or XML value. The result of the function is an integer between 1 and 12. If the argument can be null, the result can be null; if the argument is null, the result is the null value.
Syntax
MONTH ( expression )
Example
Select all rows from the EMPLOYEE table for people who were born (BIRTHDATE) in DECEMBER.
SELECT * FROM EMPLOYEE WHERE MONTH(BIRTHDATE) = 12
NULLIF expressions
Use the NULLIF expressions for conditional expressions in Derby.
NULLIF expression syntax
NULLIF ( L, R )
The NULLIF expression is very similar to the CASE expression. For example:
NULLIF(V1,V2)
is equivalent to the following CASE expression:
CASE WHEN V1=V2 THEN NULL ELSE V1 END
PI function
The PI function returns a value that is closer than any other value to pi.
The constant pi is the ratio of the circumference of a circle to the diameter of a circle.
The data type of the returned value is a DOUBLE PRECISION number.
Syntax
PI ( )
RADIANS function
The RADIANS function converts a specified number from degrees to radians.
The specified number is an angle measured in degrees, which is converted to an approximately equivalent angle measured in radians. The specified number must be a DOUBLE PRECISION number.
Attention: The conversion from degrees to radians is not exact.
The data type of the returned value is a DOUBLE PRECISION number.
Syntax
RADIANS ( number )
RANDOM function
The RANDOM function returns a random number.
The RANDOM function returns a DOUBLE PRECISION number with positive sign, greater than or equal to zero (0), and less than one (1.0).
Syntax
RANDOM()
RAND function
The RAND function returns a random number given a seed number
The RAND function returns a DOUBLE PRECISION number with positive sign, greater than or equal to zero (0), and less than one (1.0), given an INTEGER seed number.
Syntax
RAND( seed )
ROW_NUMBER function
The ROW_NUMBER function returns the row number over a named or unnamed window specification.
The ROW_NUMBER function does not take any arguments, and for each row over the window it returns an ever increasing BIGINT. It is normally used to limit the number of rows returned for a query. The LIMIT keyword used in other databases is not defined in the SQL standard, and is not supported.
 
Derby does not currently allow the named or unnamed window specification to be specified in the OVER() clause, but requires an empty parenthesis. This means the function is evaluated over the entire result set.
 
The ROW_NUMBER function cannot currently be used in a WHERE clause.
 
Derby does not currently support ORDER BY in subqueries, so there is currently no way to guarantee the order of rows in the SELECT subquery. An optimizer override can be used to force the optimizer to use an index ordered on the desired column(s) if ordering is a firm requirement.
The data type of the returned value is a BIGINT number.
Syntax
ROW_NUMBER() OVER ()
Example
To limit the number of rows returned from a query to the 10 first rows of table T, use the following query:
SELECT * FROM ( SELECT ROW_NUMBER() OVER () AS R, T.* FROM T ) AS TR WHERE R <= 10;
RTRIM function
RTRIM removes blanks from the end of a character string expression.
Syntax
RTRIM(CharacterExpression)
A CharacterExpression is a CHAR, VARCHAR, or LONG VARCHAR data type, any built-in type that is implicitly converted to a string.
RTRIM returns NULL if CharacterExpression evaluates to null.
-- returns ' asdf' VALUES RTRIM(' asdf ') -- returns 'asdf' VALUES RTRIM('asdf ')
SECOND function
The SECOND function returns the seconds part of a value.
The argument must be a time, timestamp, or a valid character string representation of a time or timestamp that is not a CLOB, LONG VARCHAR, or XML value. The result of the function is an integer between 0 and 59. If the argument can be null, the result can be null. If the argument is null, the result is 0.
Syntax
SECOND ( expression )
Example
The RECEIVED column contains a timestamp that has an internal value equivalent to 2005-12-25-17.12.30.000000. To return only the seconds part of the timestamp, use the following syntax:
SECOND(RECEIVED)
The value 30 is returned.
SESSION_USER function
SESSION_USER returns the authorization identifier or name of the current user. If there is no current user, it returns APP.
USER, CURRENT_USER, and SESSION_USER are synonyms.
Syntax
SESSION_USER
VALUES SESSION_USER
SIGN function
The SIGN function returns the sign of the specified number.
The specified number is the number you want the sign of. The specified number must be a DOUBLE PRECISION number.
The data type of the returned value is INTEGER.
 
If the specified number is NULL, the result of this function is NULL.
 
If the specified number is zero (0), the result of this function is zero (0).
 
If the specified number is greater than zero (0), the result of this function is plus one (+1).
 
If the specified number is less than zero (0), the result of this function is minus one (-1).
Syntax
SIGN ( number )
SIN function
The SIN function returns the sine of a specified number.
The specified number is the angle, in radians, that you want the sine for. The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of this function is NULL.
 
If the specified number is zero (0), the result of this function is zero.
The data type of the returned value is a DOUBLE PRECISION number.
Syntax
SIN ( number )
SINH function
The SINH function returns the hyperbolic sine of a specified number.
The specified number is the angle, in radians, that you want the hyperbolic sine for. The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of this function is NULL.
 
If the specified number is zero (0), the result of this function is zero.
The data type of the returned value is a DOUBLE PRECISION number.
Syntax
SIN ( number )
SMALLINT function
The SMALLINT function returns a small integer representation of a number or character string in the form of a small integer constant.
Syntax
SMALLINT ( NumericExpression | CharacterExpression )
NumericExpression
An expression that returns a value of any built-in numeric data type. If the argument is a NumericExpression, the result is the same number that would occur if the argument were assigned to a small integer column or variable. If the whole part of the argument is not within the range of small integers, an error occurs. The decimal part of the argument is truncated if present.
CharacterExpression
An expression that returns a character string value of length not greater than the maximum length of a character constant. Leading and trailing blanks are eliminated and the resulting string must conform to the rules for forming an SQL integer constant. However, the value of the constant must be in the range of small integers. The character string cannot be a long string. If the argument is a CharacterExpression, the result is the same number that would occur if the corresponding integer constant were assigned to a small integer column or variable.
The result of the function is a small integer. If the argument can be null, the result can be null. If the argument is null, the result is the null value.
Example
To determine the small integer representation of the number 32767.99, use this clause:
VALUES SMALLINT (32767.99)
The result is 32767.
To determine the small integer representation of the number 1, use this clause:
VALUES SMALLINT (1)
The result is 1.
SQRT function
Returns the square root of a floating point number; only the built-in types REAL, FLOAT, and DOUBLE PRECISION are supported. The return type for SQRT is the type of the parameter.
Note: To execute SQRT on other data types, you must cast them to floating point types.
Syntax
SQRT(FloatingPointExpression)
-- throws an exception if any row stores a negative number: VALUES SQRT(3421E+09) -- returns the square root of an INTEGER after casting it as a -- floating point data type: SELECT SQRT(myDoubleColumn) FROM MyTable VALUES SQRT (CAST(25 AS FLOAT));
SUBSTR function
The SUBSTR function acts on a character string expression or a bit string expression. The type of the result is a VARCHAR in the first case and VARCHAR FOR BIT DATA in the second case. The length of the result is the maximum length of the source type.
Syntax
SUBSTR({ CharacterExpression }, StartPosition [, LengthOfString ] )
The parameter startPosition and the optional parameter lengthOfString are both integer expressions. The first character or bit has a startPosition of 1. If you specify 0, Derby assumes that you mean 1.
The parameter characterExpression is a CHAR, VARCHAR, or LONG VARCHAR data type or any built-in type that is implicitly converted to a string (except a bit expression).
For character expressions, the startPosition and lengthOfString parameters refer to characters. For bit expressions, the startPosition and lengthOfString parameters refer to bits.
If the startPosition is positive, it refers to position from the start of the source expression (counting the first character as 1). The startPosition cannot be a negative number.
If the lengthOfString is not specified, SUBSTR returns the substring of the expression from the startPosition to the end of the source expression. If lengthOfString is specified, SUBSTR returns a VARCHAR or VARBIT of length lengthOfString starting at the startPosition. The SUBSTR function returns an error if you specify a negative number for the parameter lengthOfString.
Examples
To return a substring of the word hello, starting at the second character and continuing until the end of the word, use the following clause:
VALUES SUBSTR('hello', 2)
The result is 'ello'.
To return a substring of the word hello, starting at the first character and continuing for two characters, use the following clause:
VALUES SUBSTR('hello',1,2)
The result is 'he'.
SUM function
SUM is an aggregate function that evaluates the sum of the expression over a set of rows (see Aggregates (set functions)). SUM is allowed only on expressions that evaluate to numeric data types.
Syntax
SUM ( [ DISTINCT | ALL ] Expression )
The DISTINCT and ALL qualifiers eliminate or retain duplicates. ALL is assumed if neither ALL nor DISTINCT is specified. For example, if a column contains the values 1, 1, 1, 1, and 2, SUM(col) returns a greater value than SUM(DISTINCT col).
Only one DISTINCT aggregate expression per SelectExpression is allowed. For example, the following query is not allowed:
SELECT AVG (DISTINCT flying_time), SUM (DISTINCT miles) FROM Flights
The Expression can contain multiple column references or expressions, but it cannot contain another aggregate or subquery. It must evaluate to a built-in numeric data type. If an expression evaluates to NULL, the aggregate skips that value.
The resulting data type is the same as the expression on which it operates (it might overflow).
-- find all economy seats available: SELECT SUM (economy_seats) FROM Airlines; -- use SUM on multiple column references -- (find the total number of all seats purchased): SELECT SUM (economy_seats_taken + business_seats_taken + firstclass_seats_taken) as seats_taken FROM FLIGHTAVAILABILITY;
TAN function
The TAN function returns the tangent of a specified number.
The specified number is the angle, in radians, that you want the tangent for. The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of this function is NULL.
 
If the specified number is zero (0), the result of this function is zero.
The data type of the returned value is a DOUBLE PRECISION number.
Syntax
TAN ( number )
TANH function
The TANH function returns the hyperbolic tangent of a specified number.
The specified number is the angle, in radians, that you want the hyperbolic tangent for. The specified number must be a DOUBLE PRECISION number.
 
If the specified number is NULL, the result of this function is NULL.
 
If the specified number is zero (0), the result of this function is zero.
The data type of the returned value is a DOUBLE PRECISION number.
Syntax
TANH ( number )
TIME function
The TIME function returns a time from a value.
The argument must be a time, timestamp, or a valid string representation of a time or timestamp that is not a CLOB, LONG VARCHAR, or XML value. The result of the function is a time. If the argument can be null, the result can be null; if the argument is null, the result is the null value.
The other rules depend on the data type of the argument specified:
 
If the argument is a time: The result is that time.
 
If the argument is a timestamp: The result is the time part of the timestamp.
 
If the argument is a string: The result is the time represented by the string.
Syntax
TIME ( expression )
values time(current_timestamp)
If the current time is 5:03 PM, the value returned is 17:03:00.
TIMESTAMP function
The TIMESTAMP function returns a timestamp from a value or a pair of values.
The rules for the arguments depend on whether the second argument is specified:
 
If only one argument is specified: It must be a timestamp, a valid string representation of a timestamp, or a string of length 14 that is not a CLOB, LONG VARCHAR, or XML value. A string of length 14 must be a string of digits that represents a valid date and time in the form yyyyxxddhhmmss, where yyyy is the year, xx is the month, dd is the day, hh is the hour, mm is the minute, and ss is the seconds.
 
If both arguments are specified: The first argument must be a date or a valid string representation of a date and the second argument must be a time or a valid string representation of a time.
The other rules depend on whether the second argument is specified:
 
If both arguments are specified: The result is a timestamp with the date specified by the first argument and the time specified by the second argument. The microsecond part of the timestamp is zero.
 
If only one argument is specified and it is a timestamp: The result is that timestamp.
 
If only one argument is specified and it is a string: The result is the timestamp represented by that string. If the argument is a string of length 14, the timestamp has a microsecond part of zero.
Syntax
TIMESTAMP ( expression [, expression ] )
Examples
The second column in table records_table contains dates (such as 1998-12-25) and the third column contains times of day (such as 17:12:30). You can return the timestamp with this statement:
SELECT TIMESTAMP(col2, col3) FROM records_table
The following clause returns the value 1998-12-25-17:12:30.0:
VALUES TIMESTAMP('1998-12-25', '17.12.30'); 1 -------------------------- 1998-12-25 17:12:30.0
TRIM function
TRIM is a function that takes a character expression and returns that expression with leading and/or trailing pad characters removed. Optional parameters indicate whether leading, or trailing, or both leading and trailing pad characters should be removed, and specify the pad character that is to be removed.
Syntax
TRIM( [ trimOperands ] trimSource)
trimOperands ::= { trimType [ trimCharacter ] FROM | trimCharacter FROM } trimType ::= { LEADING | TRAILING | BOTH } trimCharacter ::= CharacterExpression trimSource ::= CharacterExpression
If trimType is not specified, it will default to BOTH. If trimCharacter is not specified, it will default to the space character (' '). Otherwise the trimCharacter expression must evaulate to one of the following:
 
a character string whose length is exactly one, or.
 
NULL
If either trimCharacter or trimSource evaluates to NULL, the result of the TRIM function is NULL. Otherwise, the result of the TRIM function is defined as follows:
 
If trimType is LEADING, the result will be the trimSource value with all leading occurrences of trimChar removed.
 
If trimType is TRAILING, the result will be the trimSource value with all trailing occurrences of trimChar removed.
 
If trimType is BOTH, the result will be the trimSource value with all leading *and* trailing occurrences of trimChar removed.
If trimSource's data type is CHAR or VARCHAR, the return type of the TRIM function will be VARCHAR. Otherwise the return type of the TRIM function will be CLOB.
Examples
-- returns 'derby' (no spaces) VALUES TRIM(' derby ')
-- returns 'derby' (no spaces) VALUES TRIM(BOTH ' ' FROM ' derby ')
-- returns 'derby ' (with a space at the end) VALUES TRIM(LEADING ' ' FROM ' derby ')
-- returns ' derby' (with two spaces at the beginning) VALUES TRIM(TRAILING ' ' FROM ' derby ')
-- returns NULL VALUES TRIM(cast (null as char(1)) FROM ' derby ')
-- returns NULL VALUES TRIM(' ' FROM cast(null as varchar(30)))
-- returns ' derb' (with a space at the beginning) VALUES TRIM('y' FROM ' derby')
-- results in an error because trimCharacter can only be 1 character VALUES TRIM('by' FROM ' derby')
UCASE or UPPER function
UCASE or UPPER takes a character expression as a parameter and returns a string in which all alpha characters have been converted to uppercase.
Syntax
UCASE or UPPER ( CharacterExpression )
If the parameter type is CHAR , the return type is CHAR. Otherwise, the return type is VARCHAR.
Note: UPPER and LOWER follow the database locale. See territory=ll_CC attribute for more information about specifying locale.
The length and maximum length of the returned value are the same as the length and maximum length of the parameter.
Example
To return the string aSD1#w in uppercase, use the following clause:
VALUES UPPER('aSD1#w')
The value returned is ASD1#W.
USER function
USER returns the authorization identifier or name of the current user. If there is no current user, it returns APP.
USER, CURRENT_USER, and SESSION_USER are synonyms.
Syntax
USER
VALUES USER
VARCHAR function
The VARCHAR function returns a varying-length character string representation of a character string.
Character to varchar syntax
VARCHAR (CharacterStringExpression )
CharacterStringExpression
An expression whose value must be of a character-string data type with a maximum length of 32,672 bytes.
Datetime to varchar syntax
VARCHAR (DatetimeExpression )
DatetimeExpression
An expression whose value must be of a date, time, or timestamp data type.
Using the EMPLOYEE table, select the job description (JOB defined as CHAR(8)) for Dolores Quintana as a VARCHAR equivelant:
SELECT VARCHAR(JOB) FROM EMPLOYEE WHERE LASTNAME = 'QUINTANA'
XMLEXISTS operator
XMLEXISTS is an SQL/XML operator that you can use to query XML values in SQL.
The XMLEXISTS operator has two arguments, an XML query expression and a Derby XML value.
Syntax
XMLEXISTS ( xquery-string-literal PASSING BY REF xml-value-expression [ BY REF ] )
xquery-string-literal
Must be specified as a string literal. If this argument is specified as a parameter, an expression that is not a literal, or a literal that is not a string (for example an integer), Derby throws an error. The xquery-string-literal argument must also be an XPath expression that is supported by Apache Xalan. Derby uses Apache Xalan to evaluate all XML query expressions. Because Xalan does not support full XQuery, neither does Derby. If Xalan is unable to compile or execute the query argument, Derby catches the error that is thrown by Xalan and throws the error as a SQLException. For more on XPath and XQuery expressions, see these Web sites: http://www.w3.org/TR/xpath and http://www.w3.org/TR/xquery/.
xml-value-expression
Must be an XML data value and must constitute a well-formed SQL/XML document. The xml-value-expression argument cannot be a parameter. Derby does not perform implicit parsing nor casting of XML values, so use of strings or any other data type results in an error. If the argument is a sequence that is returned by the DerbyXMLQUERY operator, the argument is accepted if it is a sequence of exactly one node that is a document node. Otherwise Derby throws an error.
BY REF
Optional keywords that describe the only value passing mechanism supported by Derby. Since BY REF is also the default passing mechanism, the XMLEXISTS operator behaves the same whether the keywords are present or not. For more information on passing mechanisms, see the SQL/XML specification.
Operator results and combining with other operators
The result of the XMLEXISTS operator is a SQL boolean value that is based on the results from evaluating the xquery-string-literal against the xml-value-expression. The XMLEXISTS operator returns:
UNKNOWN
When the xml-value-expression is null.
TRUE
When the evaluation of the specified query expression against the specified xml-value returns a non-empty sequence of nodes or values.
FALSE
When evaluation of the specified query expression against the specified xml-value returns an empty sequence.
The XMLEXISTS operator does not return the actual results from the evaluation of the query. You must use the XMLQUERY operator to retrieve the actual results.
Since the result of the XMLEXISTS operator is an SQL boolean data type, you can use the XMLEXISTS operator wherever a boolean function is allowed. For example, you can use the XMLEXISTS operator as a check constraint in a table declaration or as a predicate in a WHERE clause.
Examples
In the x_table table, to determine if the xcol XML column for each row has an element called student with an age attribute equal to 20, use this statement:
SELECT id, XMLEXISTS('//student[@age=20]' PASSING BY REF xcol) FROM x_table
In the x_table table, to return the ID for every row whose xcol XML column is non-null and contains the element /roster/student, use this statement:
SELECT id FROM x_table WHERE XMLEXISTS('/roster/student' PASSING BY REF xcol)
You can create the x_table table with a check constraint that limits which XML values can be inserted into the xcol XML column. In this example, the constraint is that the column has at least one student element with an age attribute with a value that is less than 25. To create the table, use this statement:
CREATE TABLE x_table ( id INT, xcol XML CHECK (XMLEXISTS ('//student[@age < 25]' PASSING BY REF xcol)) )
Usage note
Derby requires that a JAXP parser (such as Apache Xerces) and Apache Xalan are listed in the Java classpath for the XML functions to work. If either the JAXP parser or Xalan is missing from the classpath, attempts to use the XMLEXISTS operator will result in an error. In some situations, you may need to take steps to place the parser and Xalan in your classpath. See "XML data types and operators" in the Java DB Developer's Guide for details.
XMLPARSE operator
XMLPARSE is a SQL/XML operator that you use to parse a character string expression into a Derby XML value.
You can use the result of this operator temporarily or you can store the result permanently in Derby XML columns. Whether temporary or permanent, you can use the XML value as an input to the other Derby XML operators, such as XMLEXISTS and XMLQUERY.
Syntax
XMLPARSE (DOCUMENT string-value-expression PRESERVE WHITESPACE)
DOCUMENT
Required keyword that describes the type of XML input that Derby can parse. Derby can only parse string expressions that constitute well-formed XML documents. This is because Derby uses a JAXP parser to parse all string values. The JAXP parser expects the string-value-expression to constitute a well-formed XML document. If the string does not constitute a well-formed document, JAXP throws an error. Derby catches the error and throws the error as a SQLException.
string-value-expression
Any expression that evaluates to a SQL character type, such as CHAR, VARCHAR, LONG VARCHAR, or CLOB. The string-value-expression argument can also be a parameter. You must use the CAST function when you specify the parameter to indicate the type of value that is bound into the parameter. Derby must verify that the parameter is the correct data type before the value is parsed as an XML document. If a parameter is specified without the CAST function, or if the CAST is to a non-character datatype, Derby throws an error.
PRESERVE WHITESPACE
Required keywords that describe how Derby handles whitespace between consecutive XML nodes. When the PRESERVE WHITESPACE keywords are used, Derby preserves whitespace as dictated by the SQL/XML rules for preserving whitespace.
For more information on what constitutes a well-formed XML document, see the following specification: http://www.w3.org/TR/REC-xml/#sec-well-formed .
Restriction: The SQL/XML standard dictates that the argument to the XMLPARSE operator can also be a binary string. However, Derby only supports character string input for the XMLPARSE operator.
Examples
To insert a simple XML document into the xcol XML column in the x_table table, use the following statement:
INSERT INTO x_table VALUES (1, XMLPARSE(DOCUMENT ' <roster> <student age="18">AB</student> <student age="23">BC</student> <student>NOAGE</student> </roster>' PRESERVE WHITESPACE) )
To insert a large XML document into the xcol XML column in the x_table table, from JDBC use the following statement:
INSERT INTO x_table VALUES (2, XMLPARSE (DOCUMENT CAST (? AS CLOB) PRESERVE WHITESPACE) )
You should bind into the statement using the setCharacterStream() method, or any other JDBC setXXX method that works for the CAST target type.
Usage note
Derby requires that a JAXP parser (such as Apache Xerces) and Apache Xalan are listed in the Java classpath for the XML functions to work. If either the JAXP parser or Xalan is missing from the classpath, attempts to use the XMLPARSE operator will result in an error. In some situations, you may need to take steps to place the parser and Xalan in your classpath. See "XML data types and operators" in the Java DB Developer's Guide for details.
XMLQUERY operator
XMLQUERY is a SQL/XML operator that you can use to query XML values in SQL.
The XMLQUERY operator has two arguments, an XML query expression and a Derby XML value.
Syntax
XMLQUERY ( xquery-string-literal PASSING BY REF xml-value-expression [ RETURNING SEQUENCE [ BY REF ] ] EMPTY ON EMPTY )
xquery-string-literal
Must be specified as a string literal. If this argument is specified as a parameter, an expression that is not a literal, or a literal that is not a string (for example an integer),Derby throws an error. The xquery-string-literal argument must also be an XPath expression that is supported by Apache Xalan. Derby uses Apache Xalan to evaluate all XML query expressions. Because Xalan does not support full XQuery, neither does Derby. If Xalan is unable to compile or execute the query argument, Derby catches the error that is thrown by Xalan and throws the error as a SQLException. For more on XPath and XQuery expressions, see these Web sites: http://www.w3.org/TR/xpath and http://www.w3.org/TR/xquery/.
xml-value-expression
Must be an XML data value and must constitute a well-formed SQL/XML document. The xml-value-expression argument cannot be a parameter. Derby does not perform implicit parsing nor casting of XML values, so use of strings or any other data type results in an error. If the argument is a sequence that is returned by a Derby XMLQUERY operation, the argument is accepted if it is a sequence of exactly one node that is a document node. Otherwise Derby throws an error.
BY REF
Optional keywords that describe the only value passing mechanism supported by Derby. Since BY REF is also the default passing mechanism, the XMLQUERY operator behaves the same whether the keywords are present or not. For more information on passing mechanisms, see the SQL/XML specification.
RETURNING SEQUENCE
Optional keywords that describe the only XML type returned by the Derby XMLQUERY operator. Since SEQUENCE is also the default return type, the XMLQUERY operator behaves the same whether the keywords are present or not. For more information on the different XML return types, see the SQL/XML specification.
EMPTY ON EMPTY
Required keywords that describe the way in which XMLQUERY handles an empty result sequence. The XMLQUERY operator returns an empty sequence exactly as the sequence is. The XMLQUERY operator does not convert the empty sequence to a null value. When an empty result sequence is serialized, the result is an empty string. Derby does not consider an empty result sequence to be a well-formed XML document.
The result of the XMLQUERY operator is a value of type XML. The result represents a sequence of XML nodes or values. Atomic values, such as strings, can be part of the result sequence. The result of an XMLQUERY operator is not guaranteed to represent a well-formed XML document and it might not be possible to insert the result of an XMLQUERY operator into an XML column. To store the result in an XML column, the result must be a sequence with exactly one item in the sequence and the item must be a well-formed document node. The result can be viewed only in serialized form by explicitly using the XMLSERIALIZE operator.
Examples
In the x_table table, to search the XML column xcol and return the students that have an age attribute that is greater than 20, use the following statement:
SELECT ID, XMLSERIALIZE( XMLQUERY('//student[@age>20]' PASSING BY REF xcol EMPTY ON EMPTY) AS VARCHAR(50)) FROM x_table
The result set for this query contains a row for every row in x_table, regardless of whether or not the XMLQUERY operator actually returns results.
In the x_table table, to search the XML column xcol and return the ages for any students named BC, use the following statement:
SELECT ID, XMLSERIALIZE( XMLQUERY('string(//student[text() = "BC"]/@age)' PASSING BY REF xcol EMPTY ON EMPTY) AS VARCHAR(50)) FROM x_table WHERE XMLEXISTS('//student[text() = "BC"]' PASSING BY REF xcol)
The result set for this query contains a row for only the rows in x_table that have a student whose name is BC.
Usage note
Derby requires that a JAXP parser (such as Apache Xerces) and Apache Xalan are listed in the Java classpath for the XML functions to work. If either the JAXP parser or Xalan is missing from the classpath, attempts to use the XMLQUERY operator will result in an error. In some situations, you may need to take steps to place the parser and Xalan in your classpath. See "XML data types and operators" in the Java DB Developer's Guide for details.
XMLSERIALIZE operator
XMLSERIALIZE is a SQL/XML operator that you can use to convert an XML type to a character type. There is no other way to convert the type of a Derby XML value.
Attention: Serialization is performed based on the SQL/XML serialization rules. These rules, combined with the fact that Derby supports only a subset of the XMLSERIALIZE syntax, dictate that the results of an XMLSERIALIZE operation are not guaranteed to be in-tact copies of the original XML text. For example, assume that [xString] is a textual representation of a well-formed XML document. You issue the following statements:
INSERT INTO x_table (id, xcol) VALUES (3, XMLPARSE(DOCUMENT '[xString]' PRESERVE WHITESPACE)); SELECT id, XMLSERIALIZE(xcol AS VARCHAR(100)) FROM x_table WHERE id = 3;
There is no guarantee that the result of the XMLSERIALIZE operator will be identical to the original [xString] representation. Certain transformations can occur as part of XMLSERIALIZE processing, and those transformations are defined in the SQL/XML specification. In some cases the result of XMLSERIALIZE might actually be the same as the original textual representation, but that is not guaranteed.
When an XMLSERIALIZE operator is specified as part of the top-level result set for a query, the result can be accessed from JDBC by using whatever JDBC getXXX methods are allowed on the string-data-type argument that is included in the XMLSERIALIZE syntax. If you attempt to select the contents of an XML value from a top-level result set without using the XMLSERIALIZE operator, Derby throws an error. Derby does not implicitly serialize XML values.
Syntax
XMLSERIALIZE ( xml-value-expression AS string-data-type )
xml-value-expression
Can be any Derby XML value, including an XML result sequence generated by the XMLQUERY operator. The xml-value-expression argument cannot be a parameter.
string-data-type
Must be a SQL character string type, such as CHAR, VARCHAR, LONG VARCHAR, or CLOB. If you specify a type that is not a valid character string type, Derby throws an error.
Examples
In the x_table table, to display the contents of the xcol XML column, use this statement:
SELECT ID, XMLSERIALIZE( xcol AS CLOB) FROM x_table
To retrieve the results from JDBC, you can use the JDBC getCharacterStream() or getString() method.
To display the results of an XMLQUERY operation, use the following statement:
SELECT ID, XMLSERIALIZE( XMLQUERY('//student[@age>20]' PASSING BY REF xcol EMPTY ON EMPTY) AS VARCHAR(50)) FROM x_table
Usage note
Derby requires that a JAXP parser (such as Apache Xerces) and Apache Xalan are listed in the Java classpath for the XML functions to work. If either the JAXP parser or Xalan is missing from the classpath, attempts to use the XMLSERIALIZE operator will result in an error. In some situations, you may need to take steps to place the parser and Xalan in your classpath. See "XML data types and operators" in the Java DB Developer's Guide for details.
YEAR function
The YEAR function returns the year part of a value. The argument must be a date, timestamp, or a valid character string representation of a date or timestamp. The result of the function is an integer between 1 and 9 999. If the argument can be null, the result can be null; if the argument is null, the result is the null value.
Syntax
YEAR ( expression )
Example
Select all the projects in the PROJECT table that are scheduled to start (PRSTDATE) and end (PRENDATE) in the same calendar year.
SELECT * FROM PROJECT WHERE YEAR(PRSTDATE) = YEAR(PRENDATE)
Built-in system functions
This section describes the different built-in system functions available with Derby.
SYSCS_UTIL.SYSCS_CHECK_TABLE system function
The SYSCS_UTIL.SYSCS_CHECK_TABLE function checks the specified table, ensuring that all of its indexes are consistent with the base table. If the table and indexes are consistent, the method returns a SMALLINT with value 1. If the table and indexes are inconsistent, the function will throw an exception.
Syntax
SMALLINT SYSCS_UTIL.SYSCS_CHECK_TABLE(IN SCHEMANAME VARCHAR(128), IN TABLENAME VARCHAR(128))
An error will occur if either SCHEMANAME or TABLENAME are null.
Examples
Check a single table:
VALUES SYSCS_UTIL.SYSCS_CHECK_TABLE('SALES', 'ORDERS');
Check all tables:
SELECT schemaname, tablename, SYSCS_UTIL.SYSCS_CHECK_TABLE(schemaname, tablename) FROM sys.sysschemas s, sys.systables t WHERE s.schemaid = t.schemaid;
SYSCS_UTIL.SYSCS_GET_DATABASE_PROPERTY system function
The SYSCS_UTIL.SYSCS_GET_DATABASE_PROPERTY function fetches the value of the specified property of the database on the current connection.
If the value that was set for the property is invalid, the SYSCS_UTIL.SYSCS_GET_DATABASE_PROPERTY function returns the invalid value, but Derby uses the default value.
Syntax
VARCHAR(32762) SYSCS_UTIL.SYSCS_GET_DATABASE_PROPERTY(IN KEY VARCHAR(128))
An error will be returned if KEY is null.
SQL example
Retrieve the value of the derby.locks.deadlockTimeout property:
VALUES SYSCS_UTIL.SYSCS_GET_DATABASE_PROPERTY('derby.locks.deadlockTimeout');
SYSCS_UTIL.SYSCS_GET_RUNTIMESTATISTICS system function
The SYSCS_UTIL.SYSCS_GET_RUNTIMESTATISTICS function returns a VARCHAR(32762) value representing the query execution plan and run time statistics for a java.sql.ResultSet. A query execution plan is a tree of execution nodes. There are a number of possible node types. Statistics are accumulated during execution at each node. The types of statistics include the amount of time spent in specific operations, the number of rows passed to the node by its children, and the number of rows returned by the node to its parent. (The exact statistics are specific to each node type.) SYSCS_UTIL.SYSCS_GET_RUNTIMESTATISTICS is most meaningful for DML statements such as SELECT, INSERT, DELETE and UPDATE.
Syntax
VARCHAR(32762) SYSCS_UTIL.SYSCS_GET_RUNTIMESTATISTICS()
Example
VALUES SYSCS_UTIL.SYSCS_GET_RUNTIMESTATISTICS()
SYSCS_UTIL.SYSCS_GET_USER_ACCESS system function
The SYSCS_UTIL.SYSCS_GET_USER_ACCESS function returns the current connection access permission for the user specified.
If no permission is explicitly set for the user, the access permission for the user is the value of the default connection mode. The default connection mode is set by using the derby.database.defaultConnectionMode property.
Syntax
SYSCS_UTIL.SYSCS_GET_USER_ACCESS (USERNAME VARCHAR(128)) RETURNS VARCHAR(128)
USERNAME
An input argument of type VARCHAR(128) that specifies the user ID in the Derby database.
The value that is returned by this function is either fullAccess, readOnlyAccess, or noAccess.
A return value of noAccess means that the connection attempt by the user will be denied because neither the derby.database.fullAccessUsers property nor the derby.database.readOnlyAccessUsers property is set for the user, and the derby.database.defaultConnectionMode property is set to noAccess.
The names of the connection permissions match the existing names in use by Derby.
Example
VALUES SYSCS_UTIL.SYSCS_GET_USER_ACCESS ('BRUNNER')
Built-in system procedures
Some built-in procedures are not compatible with SQL syntax used by other relational databases. These procedures can only be used with Derby.
SYSCS_UTIL.SYSCS_BACKUP_DATABASE system procedure
The SYSCS_UTIL.SYSCS_BACKUP_DATABASE system procedure backs up the database to a specified backup directory.
Syntax
SYSCS_UTIL.SYSCS_BACKUP_DATABASE(IN BACKUPDIR VARCHAR())
No result is returned from the procedure.
BACKUPDIR
An input argument of type VARCHAR(32672) that specifies the path to a directory, where the backup should be stored. Relative paths are resolved based on the current user directory, user.dir, of the JVM where the database backup is occurring. Relative paths are not resolved based on the derby home directory. To avoid confusion, use the absolute path.
JDBC example
The following example backs up the database to the c:/backupdir directory:
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_BACKUP_DATABASE(?)"); cs.setString(1, "c:/backupdir"); cs.execute(); cs.close();
SQL example
The following example backs up the database to the c:/backupdir directory:
CALL SYSCS_UTIL.SYSCS_BACKUP_DATABASE('c:/backupdir');
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_NOWAIT system procedure
The SYSCS_UTIL.SYSCS_BACKUP_DATABASE_NOWAIT system procedure backs up the database to a specified backup directory.
If there are any transactions in progress with unlogged operations at the start of the backup, the SYSCS_UTIL.SYSCS_BACKUP_DATABASE_NOWAIT system procedure returns an error immediately, instead of waiting for those transactions to complete.
Syntax
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_NOWAIT(IN BACKUPDIR VARCHAR())
No result is returned from the procedure.
BACKUPDIR
An input argument of type VARCHAR(32672) that specifies the path to a directory, where the backup should be stored. Relative paths are resolved based on the current user directory, user.dir, of the JVM where the database backup is occurring. Relative paths are not resolved based on the derby home directory. To avoid confusion, use the absolute path.
JDBC example
The following example backs up the database to the c:/backupdir directory:
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_BACKUP_DATABASE_NOWAIT(?)"); cs.setString(1, "c:/backupdir"); cs.execute(); cs.close();
SQL example
The following example backs up the database to the c:/backupdir directory:
CALL SYSCS_UTIL.SYSCS_BACKUP_DATABASE_NOWAIT('c:/backupdir');
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE system procedure
The SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE system procedure backs up the database to a specified backup directory and enables the database for log archive mode.
Syntax
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE (IN BACKUPDIR VARCHAR(32672), IN SMALLINT DELETE_ARCHIVED_LOG_FILES)
No result is returned from the procedure.
BACKUPDIR
An input argument of type VARCHAR(32672) that specifies the path to a directory, where the backup should be stored. Relative paths are resolved based on the current user directory, user.dir, of the JVM where the database backup is occurring. Relative paths are not resolved based on the derby home directory. To avoid confusion, use the absolute path
DELETE_ARCHIVED_LOG_FILES
If the input parameter value for the DELETE_ARCHIVED_LOG_FILES parameter is a non-zero value, online archived log files that were created before this backup will be deleted. The log files are deleted only after a successful backup.
JDBC example
The following example backs up the database to the c:/backupdir directory:
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE(?, ?)"); cs.setString(1, "c:/backupdir"); cs.setInt(2, 0); cs.execute();
SQL examples
The following example backs up the database to the c:/backupdir directory, enables log archive mode, and does not delete any existing online archived log files:
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE('c:/backupdir', 0)
The following example backs up the database to the c:/backupdir directory and, if this backup is successful, deletes existing online archived log files:
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE('c:/backupdir', 1)
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE_NOWAIT system procedure
The SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE_NOWAIT system procedure backs up the database to a specified backup directory and enables the database for log archive mode. This procedure returns an error if there are any transactions in progress that have unlogged operations at the start of the backup, instead of waiting for those transactions to complete.
Syntax
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE_NOWAIT (IN BACKUPDIR VARCHAR(32672), IN SMALLINT DELETE_ARCHIVED_LOG_FILES)
No result is returned from the procedure.
BACKUPDIR
An input argument of type VARCHAR(32672) that specifies the path to a directory, where the backup should be stored. Relative paths are resolved based on the current user directory, user.dir, of the JVM where the database backup is occurring. Relative paths are not resolved based on the derby home directory. To avoid confusion, use the absolute path.
DELETE_ARCHIVED_LOG_FILES
If the input parameter value for the DELETE_ARCHIVED_LOG_FILES parameter is a non-zero value, online archived log files that were created before this backup will be deleted. The log files are deleted only after a successful backup.
JDBC example
The following example backs up the database to the c:/backupdir directory and enables log archive mode:
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE_NOWAIT(?, ?)"); cs.setString(1, "c:/backupdir"); cs.setInt(2, 0); cs.execute();
SQL examples
The following example backs up the database to the c:/backupdir directory, enables log archive mode, and does not delete any existing online archived log files:
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE_NOWAIT('c:/backupdir', 0)
The following example backs up the database to the c:/backupdir directory and, if this backup is successful, deletes existing online archived log files:
SYSCS_UTIL.SYSCS_BACKUP_DATABASE_AND_ENABLE_LOG_ARCHIVE_MODE_NOWAIT('c:/backupdir', 1)
SYSCS_UTIL.SYSCS_EMPTY_STATEMENT_CACHE system procedure
The SYSCS_UTIL.SYSCS_EMPTY_STATEMENT_CACHE stored procedure removes as many compiled statements (plans) as possible from the database-wide statement cache. The procedure does not remove statements related to currently executing queries or to activations that are about to be garbage collected, so the cache is not guaranteed to be completely empty after a call to this procedure.
Syntax
SYSCS_UTIL.SYSCS_EMPTY_STATEMENT_CACHE()
JDBC Example
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_EMPTY_STATEMENT_CACHE()"); cs.execute(); cs.close();
SQL Example
CALL SYSCS_UTIL.SYSCS_EMPTY_STATEMENT_CACHE();
SYSCS_UTIL.SYSCS_CHECKPOINT_DATABASE system procedure
The SYSCS_UTIL.SYSCS_CHECKPOINT_DATABASE system procedure checkpoints the database by flushing all cached data to disk.
Syntax
SYSCS_UTIL.SYSCS_CHECKPOINT_DATABASE()
No result is returned by this procedure.
JDBC example
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_CHECKPOINT_DATABASE()"); cs.execute(); cs.close();
SQL Example
CALL SYSCS_UTIL.SYSCS_CHECKPOINT_DATABASE();
SYSCS_UTIL.SYSCS_COMPRESS_TABLE system procedure
Use the SYSCS_UTIL.SYSCS_COMPRESS_TABLE system procedure to reclaim unused, allocated space in a table and its indexes. Typically, unused allocated space exists when a large amount of data is deleted from a table, or indexes are updated. By default, Derby does not return unused space to the operating system. For example, once a page has been allocated to a table or index, it is not automatically returned to the operating system until the table or index is destroyed. SYSCS_UTIL.SYSCS_COMPRESS_TABLE allows you to return unused space to the operating system.
The SYSCS_UTIL.SYSCS_COMPRESS_TABLE system procedure updates statistics on all indexes as part of the index rebuilding process.
Syntax
SYSCS_UTIL.SYSCS_COMPRESS_TABLE (IN SCHEMANAME VARCHAR(128), IN TABLENAME VARCHAR(128), IN SEQUENTIAL SMALLINT)
SCHEMANAME
An input argument of type VARCHAR(128) that specifies the schema of the table. Passing a null will result in an error.
TABLENAME
An input argument of type VARCHAR(128) that specifies the table name of the table. The string must exactly match the case of the table name, and the argument of "Fred" will be passed to SQL as the delimited identifier 'Fred'. Passing a null will result in an error.
SEQUENTIAL
A non-zero input argument of type SMALLINT will force the operation to run in sequential mode, while an argument of 0 will force the operation not to run in sequential mode. Passing a null will result in an error.
SQL example
To compress a table called CUSTOMER in a schema called US, using the SEQUENTIAL option:
call SYSCS_UTIL.SYSCS_COMPRESS_TABLE('US', 'CUSTOMER', 1)
Java example
To compress a table called CUSTOMER in a schema called US, using the SEQUENTIAL option:
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_COMPRESS_TABLE(?, ?, ?)"); cs.setString(1, "US"); cs.setString(2, "CUSTOMER"); cs.setShort(3, (short) 1); cs.execute();
If the SEQUENTIAL parameter is not specified, Derby rebuilds all indexes concurrently with the base table. If you do not specify the SEQUENTIAL argument, this procedure can be memory-intensive and use a lot of temporary disk space (an amount equal to approximately two times the used space plus the unused, allocated space). This is because Derby compresses the table by copying active rows to newly allocated space (as opposed to shuffling and truncating the existing space). The extra space used is returned to the operating system on COMMIT.
When SEQUENTIAL is specified, Derby compresses the base table and then compresses each index sequentially. Using SEQUENTIAL uses less memory and disk space, but is more time-intensive. Use the SEQUENTIAL argument to reduce memory and disk space usage.
SYSCS_UTIL.SYSCS_COMPRESS_TABLE cannot release any permanent disk space back to the operating system until a COMMIT is issued. This means that the space occupied by both the base table and its indexes cannot be released. Only the disk space that is temporarily claimed by an external sort can be returned to the operating system prior to a COMMIT.
Tip: We recommend that you issue the SYSCS_UTIL.SYSCS_COMPRESS_TABLE system procedure in the auto-commit mode.
Note: This procedure acquires an exclusive table lock on the table being compressed. All statement plans dependent on the table or its indexes are invalidated. For information on identifying unused space, see the Java DB Server and Administration Guide.
SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE system procedure
Use the SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE system procedure to reclaim unused, allocated space in a table and its indexes. Typically, unused allocated space exists when a large amount of data is deleted from a table and there has not been any subsequent inserts to use the space created by the deletes. By default, Derby does not return unused space to the operating system. For example, once a page has been allocated to a table or index, it is not automatically returned to the operating system until the table or index is destroyed. SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE allows you to return unused space to the operating system.
This system procedure can be used to force three levels of in-place compression of a SQL table: PURGE_ROWS, DEFRAGMENT_ROWS, and TRUNCATE_END. Unlike SYSCS_UTIL.SYSCS_COMPRESS_TABLE(), all work is done in place in the existing table/index.
Syntax
SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE( IN SCHEMANAME VARCHAR(128), IN TABLENAME VARCHAR(128), IN PURGE_ROWS SMALLINT, IN DEFRAGMENT_ROWS SMALLINT, IN TRUNCATE_END SMALLINT )
SCHEMANAME
An input argument of type VARCHAR(128) that specifies the schema of the table. Passing a null will result in an error.
TABLENAME
An input argument of type VARCHAR(128) that specifies the table name of the table. The string must exactly match the case of the table name, and the argument of "Fred" will be passed to SQL as the delimited identifier 'Fred'. Passing a null will result in an error.
PURGE_ROWS
If PURGE_ROWS is set to a non-zero value, then a single pass is made through the table which will purge committed deleted rows from the table. This space is then available for future inserted rows, but remains allocated to the table. As this option scans every page of the table, its performance is linearly related to the size of the table.
DEFRAGMENT_ROWS
If DEFRAGMENT_ROWS is set to a non-zero value, then a single defragment pass is made which will move existing rows from the end of the table towards the front of the table. The goal of defragmentation is to empty a set of pages at the end of the table which can then be returned to the operating system by the TRUNCATE_END option. It is recommended to only run DEFRAGMENT_ROWS if also specifying the TRUNCATE_END option. The DEFRAGMENT_ROWS option scans the whole table and needs to update index entries for every base table row move, so the execution time is linearly related to the size of the table.
TRUNCATE_END
If TRUNCATE_END is set to a non-zero value, then all contiguous pages at the end of the table will be returned to the operating system. Running the PURGE_ROWS and/or DEFRAGMENT_ROWS options may increase the number of pages affected. This option by itself performs no scans of the table.
SQL example
To compress a table called CUSTOMER in a schema called US, using all available compress options:
call SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE('US', 'CUSTOMER', 1, 1, 1);
To return the empty free space at the end of the same table, the following call will run much quicker than running all options but will likely return much less space:
call SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE('US', 'CUSTOMER', 0, 0, 1);
Java example
To compress a table called CUSTOMER in a schema called US, using all available compress options:
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE(?, ?, ?, ?, ?)"); cs.setString(1, "US"); cs.setString(2, "CUSTOMER"); cs.setShort(3, (short) 1); cs.setShort(4, (short) 1); cs.setShort(5, (short) 1); cs.execute();
To return the empty free space at the end of the same table, the following call will run much quicker than running all options but will likely return much less space:
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE(?, ?, ?, ?, ?)"); cs.setString(1, "US"); cs.setString(2, "CUSTOMER"); cs.setShort(3, (short) 0); cs.setShort(4, (short) 0); cs.setShort(5, (short) 1); cs.execute();
Tip: We recommend that you issue the SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE system procedure in the auto-commit mode.
Note: This procedure acquires an exclusive table lock on the table being compressed. All statement plans dependent on the table or its indexes are invalidated. For information on identifying unused space, see the Java DB Server and Administration Guide.
SYSCS_UTIL.SYSCS_DISABLE_LOG_ARCHIVE_MODE system procedure
The SYSCS_UTIL.SYSCS_DISABLE_LOG_ARCHIVE_MODE system procedure disables the log archive mode and deletes any existing online archived log files if the DELETE_ARCHIVED_LOG_FILES input parameter is non-zero.
Syntax
SYSCS_UTIL.SYSCS_DISABLE_LOG_ARCHIVE_MODE(IN SMALLINT DELETE_ARCHIVED_LOG_FILES)
No result is returned from the procedure.
DELETE_ARCHIVED_LOG_FILES
If the input parameter value for the DELETE_ARCHIVED_LOG_FILES parameter is a non-zero value, then all existing online archived log files are deleted. If the parameter value is zero, then exiting online archived log files are not deleted.
JDBC example
The following example disables log archive mode for the database and deletes any existing log archive files.
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_DISABLE_LOG_ARCHIVE_MODE(?)"); cs.setInt(1, 1); cs.execute(); cs.close();
SQL examples
The following example disables log archive mode for the database and retains any existing log archive files:
CALL SYSCS_UTIL.SYSCS_DISABLE_LOG_ARCHIVE_MODE DELETE_ARCHIVED_LOG_FILES(0);
The following example disables log archive mode for the database and deletes any existing log archive files:
CALL SYSCS_UTIL.SYSCS_DISABLE_LOG_ARCHIVE_MODE DELETE_ARCHIVED_LOG_FILES(1);
SYSCS_UTIL.SYSCS_EXPORT_TABLE system procedure
The SYSCS_UTIL.SYSCS_EXPORT_TABLE system procedure exports all of the data from a table to an operating system file.
For security concerns, and to avoid accidental file damage, this EXPORT procedure does not export data into an existing file. You must specify a filename in the EXPORT procedure that does not exist. When you run the procedure the file is created and the data is exported into the new file.
The data is exported using a delimited file format.
Syntax
SYSCS_UTIL.SYSCS_EXPORT_TABLE (IN SCHEMANAME VARCHAR(128), IN TABLENAME VARCHAR(128), IN FILENAME VARCHAR(32672), IN COLUMNDELIMITER CHAR(1), IN CHARACTERDELIMITER CHAR(1), IN CODESET VARCHAR(128))
No result is returned from the procedure.
SCHEMANAME
An input argument of type VARCHAR(128) that specifies the schema name of the table. Passing a NULL value will use the default schema name.
TABLENAME
An input argument of type VARCHAR(128) that specifies the name of the table/view from which the data is to be exported. Passing a null will result in an error.
FILENAME
Specifies the name of a new file to which the data is to be exported. If the path is omitted, the current working directory is used. If the name of a file that already exists is specified, the export procedure returns an error. The specified location of the file should refer to the server-side location if you are using the Network Server. Specifying a NULL value results in an error. The FILENAME parameter takes an input argument that is a VARCHAR (32672) data type.
COLUMNDELIMITER
An input argument of type CHAR(1) that specifies a column delimiter. The specified character is used in place of a comma to signal the end of a column. Passing a NULL value will use the default value; the default value is a comma (,).
CHARACTERDELIMITER
An input argument of type CHAR(1) that specifies a character delimiter. The specified character is used in place of double quotation marks to enclose a character string. Passing a NULL value will use the default value; the default value is a double quotation mark (").
CODESET
An input argument of type VARCHAR(128) that specifies the code set of the data in the exported file. The name of the code set should be one of the Java-supported character encodings. Data is converted from the database code set to the specified code set before writing to the file. Passing a NULL value will write the data in the same code set as the JVM in which it is being executed.
If you create a schema or table name as a non-delimited identifier, you must pass the name to the export procedure using all uppercase characters. If you created a schema, table, or column name as a delimited identifier, you must pass the name to the export procedure using the same case that was used when it was created.
Usage
For additional information on using this procedure see the section "Using the bulk import and export procedures" in the Java DB Tools and Utilities Guide.
Example
The following example shows how to export information from the STAFF table in a SAMPLE database to the myfile.del file.
CALL SYSCS_UTIL.SYSCS_EXPORT_TABLE (null, 'STAFF', 'myfile.del', null, null, null);
SYSCS_UTIL.SYSCS_EXPORT_TABLE_LOBS_TO_EXTFILE system procedure
Use the SYSCS_UTIL.SYSCS_EXPORT_TABLE_LOBS_TO_EXTFILE system procedure to export all the data from a table, and place the LOB data into a separate export file. A reference to the location of the LOB data is placed in the LOB column in the main export file.
For security concerns, and to avoid accidental file damage, this EXPORT procedure does not export data into an existing file. You must specify a filename in the EXPORT procedure that does not exist. When you run the procedure the file is created and the data is exported into the new file.
The data is exported using a delimited file format.
Syntax
SYSCS_UTIL.SYSCS_EXPORT_TABLE_LOBS_TO_EXTFILE ( IN SCHEMANAME VARCHAR(128), IN TABLENAME VARCHAR(128), IN FILENAME VARCHAR(32672), IN COLUMNDELIMITER CHAR(1), IN CHARACTERDELIMITER CHAR(1), IN CODESET VARCHAR(128) IN LOBSFILENAME VARCHAR(32672) )
When you run this procedure, the column data is written to the main export file in a delimited data file format.
SCHEMANAME
Specifies the schema of the table. You can specify a NULL value to use the default schema name. The SCHEMANAME parameter takes an input argument that is a VARCHAR (128) data type.
TABLENAME
Specifies the table name of the table or view from which the data is to be exported. This table cannot be a system table or a declared temporary table. The string must exactly match the case of the table name. Specifying a NULL value results in an error. The TABLENAME parameter takes an input argument that is a VARCHAR (128) data type.
FILENAME
Specifies the name of a new file to which the data is to be exported. If the path is omitted, the current working directory is used. If the name of a file that already exists is specified, the export procedure returns an error. The specified location of the file should refer to the server-side location if you are using the Network Server. Specifying a NULL value results in an error. The FILENAME parameter takes an input argument that is a VARCHAR (32672) data type.
COLUMNDELIMITER
Specifies a column delimiter. The specified character is used in place of a comma to signify the end of a column. You can specify a NULL value to use the default value of a comma. The COLUMNDELIMITER parameter must be a CHAR (1) data type.
CHARACTERDELIMITER
Specifies a character delimiter. The specified character is used in place of double quotation marks to enclose a character string. You can specify a NULL value to use the default value of a double quotation mark. The CHARACTERDELIMITER parameter takes an input argument that is a CHAR (1) data type.
CODESET
Specifies the code set of the data in the export file. The code set name should be one of the Java-supported character encoding sets. Data is converted from the database code page to the specified code page before writing to the file. You can specify a NULL value to write the data in the same code page as the JVM in which it is being executed. The CODESET parameter takes an input argument that is a VARCHAR (128) data type.
LOBSFILENAME
Specifies the file that the large object data is exported to. If the path is omitted, the lob file is created in the same directory as the main export file. If you specify the name of an existing file, the export utility overwrites the contents of the file. The data is not appended to the file. If you are using the Network Server, the file should be in a server-side location. Specifying a NULL value results in an error. The LOBSFILENAME parameter takes an input argument that is a VARCHAR (32672) data type.
If you create a schema, table, or column name as a non-delimited identifier, you must pass the name to the export procedure using all uppercase characters. If you created a schema or table name as a delimited identifier, you must pass the name to the export procedure using the same case that was used when it was created.
Usage
For additional information on using this procedure see the section "Using the bulk import and export procedures" in the Java DB Tools and Utilities Guide.
Example exporting all data from a table, using a separate export file for the LOB data
The following example shows how to export data from the STAFF table in a sample database to the main file staff.del and the LOB export file pictures.dat.
CALL SYSCS_UTIL.SYSCS_EXPORT_TABLE_LOBS_TO_EXTFILE( 'APP', 'STAFF', 'c:\data\staff.del', ',' ,'"', 'UTF-8', 'c:\data\pictures.dat');
SYSCS_UTIL.SYSCS_EXPORT_QUERY system procedure
The SYSCS_UTIL.SYSCS_EXPORT_QUERY system procedure exports the results of a SELECT statement to an operating system file.
For security concerns, and to avoid accidental file damage, this EXPORT procedure does not export data into an existing file. You must specify a filename in the EXPORT procedure that does not exist. When you run the procedure the file is created and the data is exported into the new file.
The data is exported using a delimited file format.
Syntax
SYSCS_UTIL.SYSCS_EXPORT_QUERY(IN SELECTSTATEMENT VARCHAR(32672), IN FILENAME VARCHAR(32672), IN COLUMNDELIMITER CHAR(1), IN CHARACTERDELIMITER CHAR(1), IN CODESET VARCHAR(128))
No result is returned from the procedure.
SELECTSTATEMENT
An input argument of type VARCHAR(32672) that specifies the select statement (query) that will return the data to be exported. Passing a NULL value will result in an error.
FILENAME
Specifies the name of a new file to which the data is to be exported. If the path is omitted, the current working directory is used. If the name of a file that already exists is specified, the export procedure returns an error. The specified location of the file should refer to the server-side location if you are using the Network Server. Specifying a NULL value results in an error. The FILENAME parameter takes an input argument that is a VARCHAR (32672) data type.
COLUMNDELIMITER
An input argument of type CHAR(1) that specifies a column delimiter. The specified character is used in place of a comma to signal the end of a column. Passing a NULL value will use the default value; the default value is a comma (,).
CHARACTERDELIMITER
An input argument of type CHAR(1) that specifies a character delimiter. The specified character is used in place of double quotation marks to enclose a character string. Passing a NULL value will use the default value; the default value is a double quotation mark (").
CODESET
An input argument of type VARCHAR(128) that specifies the code set of the data in the exported file. The name of the code set should be one of the Java-supported character encodings. Data is converted from the database code set to the specified code set before writing to the file. Passing a NULL value will write the data in the same code set as the JVM in which it is being executed.
Usage
For additional information on using this procedure see the section "Using the bulk import and export procedures" in the Java DB Tools and Utilities Guide.
Example
The following example shows how to export the information about employees in Department 20 from the STAFF table in the SAMPLE database to the myfile.del file.
CALL SYSCS_UTIL.SYSCS_EXPORT_QUERY('select * from staff where dept =20', 'c:/output/awards.del', null, null, null);
SYSCS_UTIL.SYSCS_EXPORT_QUERY_LOBS_TO_EXTFILE system procedure
Use the SYSCS_UTIL.SYSCS_EXPORT_QUERY_LOBS_TO_EXTFILE system procedure to export the result of a SELECT statement to a main export file, and place the LOB data into a separate export file. A reference to the location of the LOB data is placed in the LOB column in the main export file.
For security concerns, and to avoid accidental file damage, this EXPORT procedure does not export data into an existing file. You must specify a filename in the EXPORT procedure that does not exist. When you run the procedure the file is created and the data is exported into the new file.
The data is exported using a delimited file format.
Syntax
SYSCS_UTIL.SYSCS_EXPORT_QUERY_LOBS_TO_EXTFILE ( IN SELECTSTATEMENT VARCHAR(32672), IN FILENAME VARCHAR(32672), IN COLUMNDELIMITER CHAR(1), IN CHARACTERDELIMITER CHAR(1), IN CODESET VARCHAR(128) IN LOBSFILENAME VARCHAR(32672) )
When you run this procedure, the column data is written to the main export file in a delimited data file format.
SELECTSTATEMENT
Specifies the SELECT statement query that returns the data to be exported. Specifying a NULL value will result in an error. The SELECTSTATEMENT parameter takes an input argument that is a VARCHAR (32672) data type.
FILENAME
Specifies the name of a new file to which the data is to be exported. If the path is omitted, the current working directory is used. If the name of a file that already exists is specified, the export procedure returns an error. The specified location of the file should refer to the server-side location if you are using the Network Server. Specifying a NULL value results in an error. The FILENAME parameter takes an input argument that is a VARCHAR (32672) data type.
COLUMNDELIMITER
Specifies a column delimiter. The specified character is used in place of a comma to signify the end of a column. You can specify a NULL value to use the default value of a comma. The COLUMNDELIMITER parameter must be a CHAR (1) data type.
CHARACTERDELIMITER
Specifies a character delimiter. The specified character is used in place of double quotation marks to enclose a character string. You can specify a NULL value to use the default value of a double quotation mark. The CHARACTERDELIMITER parameter takes an input argument that is a CHAR (1) data type.
CODESET
Specifies the code set of the data in the export file. The code set name should be one of the Java-supported character encoding sets. Data is converted from the database code page to the specified code page before writing to the file. You can specify a NULL value to write the data in the same code page as the JVM in which it is being executed. The CODESET parameter takes an input argument that is a VARCHAR (128) data type.
LOBSFILENAME
Specifies the file that the large object data is exported to. If the path is omitted, the lob file is created in the same directory as the main export file. If you specify the name of an existing file, the export utility overwrites the contents of the file. The data is not appended to the file. If you are using the Network Server, the file should be in a server-side location. Specifying a NULL value results in an error. The LOBSFILENAME parameter takes an input argument that is a VARCHAR (32672) data type.
Usage
For additional information on using this procedure see the section "Using the bulk import and export procedures" in the Java DB Tools and Utilities Guide.
Example exporting data from a query using a separate export file for the LOB data
The following example shows how to export employee data in department 20 from the STAFF table in a sample database to the main file staff.del and the lob data to the file pictures.dat.
CALL SYSCS_UTIL.SYSCS_EXPORT_QUERY_LOBS_TO_EXTFILE( 'SELECT * FROM STAFF WHERE dept=20', 'c:\data\staff.del', ',' ,'"', 'UTF-8','c:\data\pictures.dat');
SYSCS_UTIL.SYSCS_IMPORT_DATA system procedure
The SYSCS_UTIL.SYSCS_IMPORT_DATA system procedure imports data to a subset of columns in a table. You choose the subset of columns by specifying insert columns. This procedure is also used to import a subset of column data from a file by specifying column indexes.
Syntax
SYSCS_UTIL.SYSCS_IMPORT_DATA (IN SCHEMANAME VARCHAR(128), IN TABLENAME VARCHAR(128), IN INSERTCOLUMNS VARCHAR(32672), IN COLUMNINDEXES VARCHAR(32672), IN FILENAME VARCHAR(32672), IN COLUMNDELIMITER CHAR(1), IN CHARACTERDELIMITER CHAR(1), IN CODESET VARCHAR(128), IN REPLACE SMALLINT)
No result is returned from the procedure.
SCHEMANAME
An input argument of type VARCHAR(128) that specifies the schema of the table. Passing a NULL value will use the default schema name.
TABLENAME
An input argument of type VARCHAR (128) that specifies the table name of the table into which the data is to be imported. This table cannot be a system table or a declared temporary table. Passing a null will result in an error.
INSERTCOLUMNS
An input argument of type VARCHAR (32762) that specifies the column names (separated by commas) of the table into which the data is to be imported. Passing a NULL value will import the data into all of the columns of the table.
COLUMNINDEXES
An input argument of type VARCHAR (32762) that specifies the indexes (numbered from 1 and separated by commas) of the input data fields to be imported. Passing a NULL value will use all of the input data fields in the file.
FILENAME
An input argument of type VARCHAR(32672) that specifies the file that contains the data to be imported. If you do not specify a path, the current working directory is used. Passing a NULL value will result in an error.
COLUMNDELIMITER
An input argument of type CHAR(1) that specifies a column delimiter. The specified character is used in place of a comma to signal the end of a column. Passing a NULL value will use the default value; the default value is a comma (,).
CHARACTERDELIMITER
An input argument of type CHAR(1) that specifies a character delimiter. The specified character is used in place of double quotation marks to enclose a character string. Passing a NULL value will use the default value; the default value is a double quotation mark (").
CODESET
An input argument of type VARCHAR(128) that specifies the code set of the data in the input file. The name of the code set should be one of the Java-supported character encodings. Data is converted from the specified code set to the database code set (utf-8). Passing a NULL value will interpret the data file in the same code set as the JVM in which it is being executed.
REPLACE
A input argument of type SMALLINT. A non-zero value will run in REPLACE mode, while a value of zero will run in INSERT mode. REPLACE mode deletes all existing data from the table by truncating the data object, and inserts the imported data. The table definition and the index definitions are not changed. You can only use the REPLACE mode if the table exists. INSERT mode adds the imported data to the table without changing the existing table data. Passing a NULL will result in an error.
If you create a schema, table, or column name as a non-delimited identifier, you must pass the name to the import procedure using all uppercase characters. If you created a schema, table, or column name as a delimited identifier, you must pass the name to the import procedure using the same case that was used when it was created.
Usage
For additional information on using this procedure see the section "Using the bulk import and export procedures" in the Java DB Tools and Utilities Guide.
Example
The following example imports some of the data fields from a delimited data file called data.del into the STAFF table:
CALL SYSCS_UTIL.SYSCS_IMPORT_DATA (NULL, 'STAFF', null, '1,3,4', 'data.del', null, null, null,0)
SYSCS_UTIL.SYSCS_IMPORT_DATA_LOBS_FROM_EXTFILE system procedure
Use the SYSCS_UTIL.SYSCS_IMPORT_DATA_LOBS_FROM_EXTFILE system procedure to import data to a subset of columns in a table, where the LOB data is stored in a separate file. The main import file contains all of the other data and a reference to the location of the LOB data.
Syntax
SYSCS_UTIL.SYSCS_IMPORT_DATA_LOBS_FROM_EXTFILE ( IN SCHEMANAME VARCHAR(128), IN TABLENAME VARCHAR(128), IN INSERTCOLUMNS VARCHAR(32672), IN COLUMNINDEXES VARCHAR(32672), IN FILENAME VARCHAR(32672), IN COLUMNDELIMITER CHAR(1), IN CHARACTERDELIMITER CHAR(1), IN CODESET VARCHAR(128), IN REPLACE SMALLINT) )
The import utility looks in the main import file for a reference to the location of the LOB data.
SCHEMANAME
Specifies the schema of the table. You can specify a NULL value to use the default schema name. The SCHEMANAME parameter takes an input argument that is a VARCHAR (128) data type.
TABLENAME
Specifies the name of the table into which the data is to be imported. This table cannot be a system table or a declared temporary table. The string must exactly match case of the table name. Specifying a NULL value results in an error. The TABLENAME parameter takes an input argument that is a VARCHAR (128) data type.
INSERTCOLUMNS
Specifies the comma separated column names of the table into which the data will be imported. You can specify a NULL value to import into all columns of the table. The INSERTCOLUMNS parameter takes an input argument that is a VARCHAR (32672) data type.
COLUMNINDEXES
Specifies the comma separated column indexes (numbered from one) of the input data fields that will be imported. You can specify a NULL value to use all input data fields in the file. The COLUMNINDEXES parameter takes an input argument that is a VARCHAR (32762) data type.
FILENAME
Specifies the name of the file that contains the data to be imported. If the path is omitted, the current working directory is used. The specified location of the file should refer to the server side location if using the Network Server. Specifying a NULL value results in an error. The fileName parameter takes an input argument that is a VARCHAR (32672) data type.
COLUMNDELIMITER
Specifies a column delimiter. The specified character is used in place of a comma to signify the end of a column. You can specify a NULL value to use the default value of a comma. The COLUMNDELIMITER parameter takes an input argument that is a CHAR (1) data type.
CHARACTERDELIMITER
Specifies a character delimiter. The specified character is used in place of double quotation marks to enclose a character string. You can specify a NULL value to use the default value of a double quotation mark. The CHARACTERDELIMITER parameter takes an input argument that is a CHAR (1) data type.
CODESET
Specifies the code set of the data in the input file. The code set name should be one of the Java-supported character encoding sets. Data is converted from the specified code set to the database code set (UTF-8). You can specify a NULL value to interpret the data file in the same code set as the JVM in which it is being executed. The CODESET parameter takes an input argument that is a VARCHAR (128) data type.
REPLACE
A non-zero value for the replace parameter will import in REPLACE mode, while a zero value will import in INSERT mode. REPLACE mode deletes all existing data from the table by truncating the table and inserts the imported data. The table definition and the index definitions are not changed. You can only import with REPLACE mode if the table already exists. INSERT mode adds the imported data to the table without changing the existing table data. Specifying a NULL value results in an error. The REPLACE parameter takes an input argument that is a SMALLINT data type.
If you create a schema, table, or column name as a non-delimited identifier, you must pass the name to the import procedure using all uppercase characters. If you created a schema, table, or column name as a delimited identifier, you must pass the name to the import procedure using the same case that was used when it was created.
Usage
This procedure will read the LOB data using the reference that is stored in the main import file. The format of the reference to the LOB stored in the main import file must be lobsFileName.Offset.length/.
 
Offset is position in the external file in bytes
 
length is the size of the LOB column data in bytes
For additional information on using this procedure see the section "Using the bulk import and export procedures" in the Java DB Tools and Utilities Guide.
Example importing data into specific columns, using a separate import file for the LOB data
The following example shows how to import data into several columns of the STAFF table. The STAFF table includes a LOB column in a sample database. The import file staff.del is a delimited data file. The staff.del file contains references that point to a separate file which contains the LOB data. The data in the import file is formatted using double quotation marks (") as the string delimiter and a comma (,) as the column delimiter. The data will be appended to the existing data in the STAFF table.
CALL SYSCS_UTIL.SYSCS_IMPORT_DATA_LOBS_FROM_EXTFILE (null, 'STAFF', 'NAME,DEPT,SALARY,PICTURE', '2,3,4,6', 'c:\data\staff.del', ',','"','UTF-8', 0);
SYSCS_UTIL.SYSCS_IMPORT_TABLE system procedure
The SYSCS_UTIL.SYSCS_IMPORT_TABLE system procedure imports data from an input file into all of the columns of a table. If the table receiving the imported data already contains data, you can either replace or append to the existing data.
Syntax
SYSCS_UTIL.SYSCS_IMPORT_TABLE (IN SCHEMANAME VARCHAR(128), IN TABLENAME VARCHAR(128), IN FILENAME VARCHAR(32672), IN COLUMNDELIMITER CHAR(1), IN CHARACTERDELIMITER CHAR(1), IN CODESET VARCHAR(128), IN REPLACE SMALLINT)
No result is returned from the procedure.
SCHEMANAME
An input argument of type VARCHAR(128) that specifies the schema of the table. Passing a NULL value will use the default schema name.
TABLENAME
An input argument of type VARCHAR (128) that specifies the table name of the table into which the data is to be imported. This table cannot be a system table or a declared temporary table. Passing a null will result in an error.
FILENAME
An input argument of type VARCHAR(32672) that specifies the file that contains the data to be imported. If you do not specify a path, the current working directory is used. Passing a NULL value will result in an error.
COLUMNDELIMITER
An input argument of type CHAR(1) that specifies a column delimiter. The specified character is used in place of a comma to signal the end of a column. Passing a NULL value will use the default value; the default value is a comma (,).
CHARACTERDELIMITER
An input argument of type CHAR(1) that specifies a character delimiter. The specified character is used in place of double quotation marks to enclose a character string. Passing a NULL value will use the default value; the default value is a double quotation mark (").
CODESET
An input argument of type VARCHAR(128) that specifies the code set of the data in the input file. The name of the code set should be one of the Java-supported character encodings. Data is converted from the specified code set to the database code set (utf-8). Passing a NULL value will interpret the data file in the same code set as the JVM in which it is being executed.
REPLACE
A input argument of type SMALLINT. A non-zero value will run in REPLACE mode, while a value of zero will run in INSERT mode. REPLACE mode deletes all existing data from the table by truncating the data object, and inserts the imported data. The table definition and the index definitions are not changed. INSERT mode adds the imported data to the table without changing the existing table data. Passing a NULL will result in an error.
If you create a schema, table, or column name as a non-delimited identifier, you must pass the name to the import procedure using all uppercase characters. If you created a schema, table, or column name as a delimited identifier, you must pass the name to the import procedure using the same case that was used when it was created.
Usage
For additional information on using this procedure see the section "Using the bulk import and export procedures" in the Java DB Tools and Utilities Guide.
Example
The following example imports data into the STAFF table from a delimited data file called myfile.del with the percentage character (%) as the string delimiter, and a semicolon (;) as the column delimiter:
CALL SYSCS_UTIL.SYSCS_IMPORT_TABLE (null, 'STAFF', 'c:/output/myfile.del', ';', '%', null,0);
SYSCS_UTIL.SYSCS_IMPORT_TABLE_LOBS_FROM_EXTFILE system procedure
Use the SYSCS_UTIL.SYSCS_IMPORT_TABLE_LOBS_FROM_EXTFILE system procedure to import data to a table, where the LOB data is stored in a separate file. The main import file contains all of the other data and a reference to the location of the LOB data.
Syntax
SYSCS_UTIL.SYSCS_IMPORT_TABLE_LOBS_FROM_EXTFILE ( IN SCHEMANAME VARCHAR(128), IN TABLENAME VARCHAR(128), IN FILENAME VARCHAR(32672), IN COLUMNDELIMITER CHAR(1), IN CHARACTERDELIMITER CHAR(1), IN CODESET VARCHAR(128), IN REPLACE SMALLINT) )
The import utility looks in the main import file for a reference to the location of the LOB data.
SCHEMANAME
Specifies the schema of the table. You can specify a NULL value to use the default schema name. The SCHEMANAME parameter takes an input argument that is a VARCHAR (128) data type.
TABLENAME
Specifies the name of the table into which the data is to be imported. This table cannot be a system table or a declared temporary table. The string must exactly match case of the table name. Specifying a NULL value results in an error. The TABLENAME parameter takes an input argument that is a VARCHAR (128) data type.
FILENAME
Specifies the name of the file that contains the data to be imported. If the path is omitted, the current working directory is used. The specified location of the file should refer to the server side location if using the Network Server. Specifying a NULL value results in an error. The FILENAME parameter takes an input argument that is a VARCHAR (32672) data type.
COLUMNDELIMITER
Specifies a column delimiter. The specified character is used in place of a comma to signify the end of a column. You can specify a NULL value to use the default value of a comma. The COLUMNDELIMITER parameter takes an input argument that is a CHAR (1) data type.
CHARACTERDELIMITER
Specifies a character delimiter. The specified character is used in place of double quotation marks to enclose a character string. You can specify a NULL value to use the default value of a double quotation mark. The CHARACTERDELIMITER parameter takes an input argument that is a CHAR (1) data type.
CODESET
Specifies the code set of the data in the input file. The code set name should be one of the Java-supported character encoding sets. Data is converted from the specified code set to the database code set (UTF-8). You can specify a NULL value to interpret the data file in the same code set as the JVM in which it is being executed. The CODESET parameter takes an input argument that is a VARCHAR (128) data type.
REPLACE
A non-zero value for the replace parameter will import in REPLACE mode, while a zero value will import in INSERT mode. REPLACE mode deletes all existing data from the table by truncating the table and inserts the imported data. The table definition and the index definitions are not changed. You can only import with REPLACE mode if the table already exists. INSERT mode adds the imported data to the table without changing the existing table data. Specifying a NULL value results in an error. The REPLACE parameter takes an input argument that is a SMALLINT data type.
If you create a schema, table, or column name as a non-delimited identifier, you must pass the name to the import procedure using all uppercase characters. If you created a schema, table, or column name as a delimited identifier, you must pass the name to the import procedure using the same case that was used when it was created.
Usage
This procedure will read the LOB data using the reference that is stored in the main import file. If you are importing from a non-Derby source, the format of the reference to the LOB stored in the main import file must be lobsFileName.Offset.length/.
 
Offset is position in the external file in bytes
 
length is the size of the LOB column data in bytes
For additional information on using this procedure see the section "Using the bulk import and export procedures" in the Java DB Tools and Utilities Guide.
Example importing data from a main import file that contains references which point to a separate file that contains LOB data
The following example shows how to import data into the STAFF table in a sample database from a delimited data file staff.del. This example defines a comma as the column delimiter. The data will be appended to the existing data in the table.
CALL SYSCS_UTIL.SYSCS_IMPORT_TABLE_LOBS_FROM_EXTFILE( 'APP','STAFF','c:\data\staff.del',',','"','UTF-8',0);
SYSCS_UTIL.SYSCS_FREEZE_DATABASE system procedure
The SYSCS_UTIL.SYSCS_FREEZE_DATABASE system procedure temporarily freezes the database for backup.
Syntax
SYSCS_UTIL.SYSCS_FREEZE_DATABASE()
No result set is returned by this procedure.
Example
String backupdirectory = "c:/mybackups/" + JCalendar.getToday(); CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_FREEZE_DATABASE()"); cs.execute(); cs.close(); // user supplied code to take full backup of "backupdirectory" // now unfreeze the database once backup has completed: CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_UNFREEZE_DATABASE()"); cs.execute(); cs.close();
SYSCS_UTIL.SYSCS_UNFREEZE_DATABASE system procedure
The SYSCS_UTIL.SYSCS_UNFREEZE_DATABASE system procedure unfreezes a database after backup.
Syntax
SYSCS_UTIL.SYSCS_UNFREEZE_DATABASE()
No result set is returned by this procedure.
Example
String backupdirectory = "c:/mybackups/" + JCalendar.getToday(); CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_FREEZE_DATABASE()"); cs.execute(); cs.close(); // user supplied code to take full backup of "backupdirectory" // now unfreeze the database once backup has completed: CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_UNFREEZE_DATABASE()"); cs.execute(); cs.close();
SYSCS_UTIL.SYSCS_RELOAD_SECURITY_POLICY system procedure
The SYSCS_UTIL.SYSCS_RELOAD_SECURITY_POLICY system procedure reloads the security policy, allowing you to fine-tune your Java security on the fly. For more information on security policies, see the section titled "Running the Network Server under the security manager" in the Java DB Server and Administration Guide and the section titled "Running Derby under a security manager" in the Java DB Developer's Guide.
Syntax
SYSCS_UTIL.SYSCS_RELOAD_SECURITY_POLICY()
No result set is returned by this procedure.
Example
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_RELOAD_SECURITY_POLICY()"); cs.execute(); cs.close();
SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY system procedure
Use the SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY system procedure to set or delete the value of a property of the database on the current connection. For information about properties, see Derby property reference.
If VALUE is not null, then the property with key value KEY is set to VALUE. If VALUE is null, then the property with key value KEY is deleted from the database property set.
If VALUE is an invalid value for the property, Derby uses the default value of the property, although SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY returns the invalid value.
Syntax
SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY(IN KEY VARCHAR(128), IN VALUE VARCHAR(32672))
This procedure does not return any results.
JDBC example
Set the derby.locks.deadlockTimeout property to a value of 10:
CallableStatement cs = conn.prepareCall ("CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY(?, ?)"); cs.setString(1, "derby.locks.deadlockTimeout"); cs.setString(2, "10"); cs.execute(); cs.close();
SQL example
Set the derby.locks.deadlockTimeout property to a value of 10:
CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY ('derby.locks.deadlockTimeout', '10')
SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS system procedure
The SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS() system procedure turns a connection's runtime statistics on or off. By default, the runtime statistics are turned off. When the runtimestatistics attribute is turned on, Derby maintains information about the execution plan for each statement executed within the connection (except for COMMIT) until the attribute is turned off. To turn the runtimestatistics attribute off, call the procedure with an argument of zero. To turn the runtimestatistics on, call the procedure with any non-zero argument.
For statements that do not return rows, the object is created when all internal processing has completed before returning to the client program. For statements that return rows, the object is created when the first next() call returns 0 rows or if a close() call is encountered, whichever comes first.
Syntax
SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS(IN SMALLINT ENABLE)
Example
-- establish a connection -- turn on RUNTIMESTATISTIC for connection: CALL SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS(1); -- execute complex query here -- step through the result sets -- access runtime statistics information: CALL SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS(0);
SYSCS_UTIL.SYSCS_SET_STATISTICS_TIMING system procedure
Statistics timing is an attribute associated with a connection that you turn on and off by using the SYSCS_UTIL.SYSCS_SET_STATISTICS_TIMING system procedure. Statistics timing is turned off by default. Turn statistics timing on only when the runtimestatistics attribute is already on. Turning statistics timing on when the runtimestatistics attribute is off has no effect.
Turn statistics timing on by calling this procedure with a non-zero argument. Turn statistics timing off by calling the procedure with a zero argument.
When statistics timing is turned on, Derby tracks the timings of various aspects of the execution of a statement. This information is included in the information returned by the SYSCS_UTIL.SYSCS_GET_RUNTIMESTATISTICS system function. When statistics timing is turned off, the SYSCS_UTIL.SYSCS_GET_RUNTIMESTATISTICS system function shows all timing values as zero.
Syntax
SYSCS_UTIL.SYSCS_SET_STATISTICS_TIMING(IN SMALLINT ENABLE)
Example
To turn the runtimestatistics attribute and then the statistics timing attribute on:
CALL SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS(1); CALL SYSCS_UTIL.SYSCS_SET_STATISTICS_TIMING(1);
SYSCS_UTIL.SYSCS_SET_USER_ACCESS system procedure
The SYSCS_UTIL.SYSCS_SET_USER_ACCESS system procedure sets the connection access permission for the user specified.
Syntax
SYSCS_UTIL.SYSCS_SET_USER_ACCESS (USERNAME VARCHAR(128), CONNECTION_PERMISSION VARCHAR(128))
USERNAME
An input argument of type VARCHAR(128) that specifies the user ID in the Derby database.
CONNECTION_PERMISSION
Valid values for CONNECTION_PERMISSION are:
fullAccess
Adds the user to the list of users with full access to the database. The value for the database property is derby.database.fullAccessUsers.
readOnlyAccess
Adds the user to the list of users with read-only access to the database. The value for the database property is derby.database.readOnlyAccessUsers.
null
Removes the user from the list of permissions, reverting the user to the default permission. You must specify null without the quotation marks.
Example
CALL SYSCS_UTIL.SYSCS_SET_USER_ACCESS ('BRUNNER', 'readOnlyAccess')
To remove the user from the list of permissions, you specify the null value without the quotation marks. For example:
CALL SYSCS_UTIL.SYSCS_SET_USER_ACCESS ('ISABEL', null)
SYSCS_UTIL.SYSCS_UPDATE_STATISTICS system procedure
The SYSCS_UTIL.SYSCS_UPDATE_STATISTICS system procedure updates the cardinality statistics, or creates the statistics if they do not exist, for the index that you specify or for all of the indexes on a table. Derby uses cardinality statistics to determine the optimal query plan during the compilation of a query. If the statistics are missing, Derby might use a query plan which is not the most efficient plan.
Once statistics have been created, they cannot be dropped and should be maintained. It is a good idea to call the SYSCS_UTIL.SYSCS_UPDATE_STATISTICS procedure when the number of distinct values in an index is likely to have changed significantly.
For more information on cardinality statistics, see "Working with cardinality statistics" in the Tuning Java DB guide.
Syntax
SYSCS_UTIL.SYSCS_UPDATE_STATISTICS(IN SCHEMANAME VARCHAR(128), IN TABLENAME VARCHAR(128), IN INDEXNAME VARCHAR(128)))
Note: You can specify null for the INDEXNAME to update any existing statistics and create statistics for those statistics that are missing.
Examples
In the following example, the system procedure updates statistics for the index PAY_DESC on the SAMP.EMPLOYEE table:
CALL SYSCS_UTIL.SYSCS_UPDATE_STATISTICS('SAMP','EMPLOYEE','PAY_DESC');
In the following example, null is specified instead of an index name. For all of the indexes, the existing statistics are updated and statistics are created for any missing statistics on the EMPLOYEE table in the SAMP schema.
CALL SYSCS_UTIL.SYSCS_UPDATE_STATISTICS('SAMP', 'EMPLOYEE', null);
SYSCS_DIAG diagnostic tables and functions
Derby provides a set of system table expressions which you can use to obtain diagnostic information about the state of the database and about the database sessions.
There are two types of diagnostic table expressions in Derby:
Diagnostic tables
Tables that are like any other table in Derby. You can specify the diagnostic table name anywhere a normal table name is allowed.
Diagnostic table functions
Functions that are like any other function in Derby. Diagnostic table functions can accept zero or more arguments, depending on the table function that you use. You must use the SQL-defined table function syntax to access these functions.
The following table shows the types and names of the diagnostic table expressions in Derby.
Table 9. System diagnostic table expressions provided by Derby
Diagnostic table expression
Type of expression
SYSCS_DIAG.CONTAINED_ROLES
Table function
SYSCS_DIAG.ERROR_LOG_READER
Table function
SYSCS_DIAG.ERROR_MESSAGES
Table
SYSCS_DIAG.LOCK_TABLE
Table
SYSCS_DIAG.SPACE_TABLE
Table function
SYSCS_DIAG.STATEMENT_CACHE
Table
SYSCS_DIAG.STATEMENT_DURATION
Table function
SYSCS_DIAG.TRANSACTION_TABLE
Table
Restriction: If you reference a diagnostic table in a DDL statement or a compression procedure, Derby returns an exception.
SYSCS_DIAG.CONTAINED_ROLES diagnostic table function
The SYSCS_DIAG.CONTAINED_ROLES diagnostic table function returns all the roles contained within the specified role. For a definition of role containment, see "Syntax for roles" in GRANT statement.
For example:
SELECT * FROM TABLE (SYSCS_DIAG.CONTAINED_ROLES(reader))
SYSCS_DIAG.ERROR_LOG_READER diagnostic table function
The SYSCS_DIAG.ERROR_LOG_READER diagnostic table function contains all the useful SQL statements that are in the derby.log file or a log file that you specify.
One use of this diagnostic table function is to determine the active transactions and the SQL statements in those transactions at a given point in time. For example, if a deadlock or lock timeout occurred you can find the timestamp (timestampConstant) in the error log.
To access the SYSCS_DIAG.ERROR_LOG_READER diagnostic table function, you must use the SQL table function syntax.
For example:
SELECT * FROM TABLE (SYSCS_DIAG.ERROR_LOG_READER()) AS T1
where T1 is a user-specified table name that is any valid identifier.
You can specify a log file name as an optional argument to the SYSCS_DIAG.ERROR_LOG_READER diagnostic table function. When you specify a log file name, the file name must be an expression whose data type maps to a Java string.
For example:
SELECT * FROM TABLE (SYSCS_DIAG.ERROR_LOG_READER('myderbyerrors.log')) AS T1
Tip: By default Derby log files contain only boot, shutdown, and error messages. See the derby.stream.error.logSeverityLevel property and the derby.language.logStatementText property for instructions on how to print more information to Derby log files. You can then query that information by using the SYSCS_DIAG.ERROR_LOG_READER diagnostic table function.
SYSCS_DIAG.ERROR_MESSAGES diagnostic table
The SYSCS_DIAG.ERROR_MESSAGES diagnostic table shows all of the SQLStates, locale-sensitive error messages, and exception severities for a Derby database. You can reference the SYSCS_DIAG.ERROR_MESSAGES diagnostic table directly in a statement.
For example:
SELECT * FROM SYSCS_DIAG.ERROR_MESSAGES
SYSCS_DIAG.LOCK_TABLE diagnostic table
The SYSCS_DIAG.LOCK_TABLE diagnostic table shows all of the locks that are currently held in the Derby database. You can reference the SYSCS_DIAG.LOCK_TABLE diagnostic table directly in a statement.
For example:
SELECT * FROM SYSCS_DIAG.LOCK_TABLE
When the SYSCS_DIAG.LOCK_TABLE diagnostic table is referenced in a statement, a snap shot of the lock table is taken. A snap shot is used so that referencing the diagnostic table does not alter the normal timing and flow of the application. It is possible that some locks will be in a transition state when the snap shot is taken.
SYSCS_DIAG.SPACE_TABLE diagnostic table function
The SYSCS_DIAG.SPACE_TABLE diagnostic table function shows the space usage of a particular table and its indexes. You can use this diagnostic table function to determine if space might be saved by compressing the table and indexes.
To access the SYSCS_DIAG.SPACE_TABLE diagnostic table function, you must use the SQL table function syntax. This diagnostic table function takes two arguments, the schemaName and the tableName. The tableName argument is required. If you do not specify the schemaName, the current schema is used.
For example, use the following query to return the space usage for all of the user tables and indexes in the database:
SELECT T2.* FROM SYS.SYSTABLES systabs, TABLE (SYSCS_DIAG.SPACE_TABLE(systabs.tablename)) AS T2 WHERE systabs.tabletype = 'T'
where T2 is a user-specified table name that is any valid identifier.
Both the schemaName and the tableName arguments must be expressions whose data types map to Java strings. If the schemaName and the tableName are non-delimited identifiers, you must specify the names in upper case.
For example:
SELECT * FROM TABLE (SYSCS_DIAG.SPACE_TABLE('MYSCHEMA', 'MYTABLE')) AS T2
SYSCS_DIAG.STATEMENT_CACHE diagnostic table
The SYSCS_DIAG.STATEMENT_CACHE diagnostic table shows the contents of the SQL statement cache. You can reference the SYSCS_DIAG.STATEMENT_CACHE diagnostic table directly in a statement.
For example: