| dbReadTable {DBI} | R Documentation |
Reads a database table to a data frame, optionally converting a column to row names and converting the column names to valid R identifiers.
dbReadTable(conn, name, ...)
conn |
A DBIConnection object, as returned by
|
name |
A character string specifying the unquoted DBMS table name,
or the result of a call to |
... |
Other parameters passed on to methods. |
dbReadTable() returns a data frame that contains the complete data
from the remote table, effectively the result of calling dbGetQuery()
with SELECT * FROM <name>.
An error is raised if the table does not exist.
An empty table is returned as a data frame with zero rows.
The presence of rownames depends on the row.names argument,
see sqlColumnToRownames() for details:
If FALSE or NULL, the returned data frame doesn't have row names.
If TRUE, a column named "row_names" is converted to row names,
an error is raised if no such column exists.
If NA, a column named "row_names" is converted to row names if it exists,
otherwise no translation occurs.
If a string, this specifies the name of the column in the remote table that contains the row names, an error is raised if no such column exists.
The default is row.names = FALSE.
If the database supports identifiers with special characters,
the columns in the returned data frame are converted to valid R
identifiers
if the check.names argument is TRUE,
otherwise non-syntactic column names can be returned unquoted.
An error is raised when calling this method for a closed
or invalid connection.
An error is raised
if name cannot be processed with dbQuoteIdentifier()
or if this results in a non-scalar.
Unsupported values for row.names and check.names
(non-scalars,
unsupported data types,
NA for check.names)
also raise an error.
The following arguments are not part of the dbReadTable() generic
(to improve compatibility across backends)
but are part of the DBI specification:
row.names
check.names
They must be provided as named arguments. See the "Value" section for details on their usage.
The name argument is processed as follows,
to support databases that allow non-syntactic names for their objects:
If an unquoted table name as string: dbReadTable() will do the
quoting,
perhaps by calling dbQuoteIdentifier(conn, x = name)
If the result of a call to dbQuoteIdentifier(): no more quoting is done
Other DBIConnection generics: DBIConnection-class,
dbDataType, dbDisconnect,
dbExecute, dbExistsTable,
dbGetException, dbGetInfo,
dbGetQuery, dbIsValid,
dbListFields, dbListResults,
dbListTables, dbRemoveTable,
dbSendQuery, dbSendStatement,
dbWriteTable
con <- dbConnect(RSQLite::SQLite(), ":memory:") dbWriteTable(con, "mtcars", mtcars[1:10, ]) dbReadTable(con, "mtcars") dbDisconnect(con)