PREPARE — prepare a statement for execution
PREPAREprepared_nameFROMstring
PREPARE prepares a statement dynamically
specified as a string for execution. This is different from the
direct SQL statement PREPARE, which can also
be used in embedded programs. The EXECUTE
command is used to execute either kind of prepared statement.
prepared_nameAn identifier for the prepared query.
string
A literal string or a host variable containing a preparable
SQL statement, one of SELECT, INSERT, UPDATE, or DELETE.
Use question marks (?) for parameter values
to be supplied at execution.
In typical usage, the string is a host
variable reference to a string containing a dynamically-constructed
SQL statement. The case of a literal string is not very useful;
you might as well just write a direct SQL PREPARE
statement.
If you do use a literal string, keep in mind that any double quotes
you might wish to include in the SQL statement must be written as
octal escapes (\042) not the usual C
idiom \". This is because the string is inside
an EXEC SQL section, so the ECPG lexer parses it
according to SQL rules not C rules. Any embedded backslashes will
later be handled according to C rules; but \"
causes an immediate syntax error because it is seen as ending the
literal.
char *stmt = "SELECT * FROM test1 WHERE a = ? AND b = ?"; EXEC SQL ALLOCATE DESCRIPTOR outdesc; EXEC SQL PREPARE foo FROM :stmt; EXEC SQL EXECUTE foo USING SQL DESCRIPTOR indesc INTO SQL DESCRIPTOR outdesc;
PREPARE is specified in the SQL standard.