| SQL {DBI} | R Documentation |
This set of classes and generics make it possible to flexibly deal with SQL
escaping needs. By default, any user supplied input to a query should be
escaped using either dbQuoteIdentifier() or dbQuoteString()
depending on whether it refers to a table or variable name, or is a literal
string.
These functions may return an object of the SQL class,
which tells DBI functions that a character string does not need to be escaped
anymore, to prevent double escaping.
The SQL class has associated the SQL() constructor function.
SQL(x)
x |
A character vector to label as being escaped SQL. |
... |
Other arguments passed on to methods. Not otherwise used. |
An object of class SQL.
DBI provides default generics for SQL-92 compatible quoting. If the database
uses a different convention, you will need to provide your own methods.
Note that because of the way that S4 dispatch finds methods and because
SQL inherits from character, if you implement (e.g.) a method for
dbQuoteString(MyConnection, character), you will also need to
implement dbQuoteString(MyConnection, SQL) - this should simply
return x unchanged.
dbQuoteIdentifier(ANSI(), "SELECT")
dbQuoteString(ANSI(), "SELECT")
# SQL vectors are always passed through as is
var_name <- SQL("SELECT")
var_name
dbQuoteIdentifier(ANSI(), var_name)
dbQuoteString(ANSI(), var_name)
# This mechanism is used to prevent double escaping
dbQuoteString(ANSI(), dbQuoteString(ANSI(), "SELECT"))