A pragma is a special instruction to the compiler. Also called a pseudoinstruction, the pragma doesn't change the meaning of a program. It simply passes information to the compiler. It is very similar, in fact, to the tuning hints you can embed in a SQL statement inside a block comment.
PL/SQL offers the following pragmas:
Tells the compiler to associate a particular error number with an identifier you have declared as an exception in your program. See Chapter 8, Exception Handlers for more information.
Tells the compiler the purity level (freedom from side effects) of a packaged program. See Chapter 17, Calling PL/SQL Functions in SQL for more information.
New to PL/SQL8. Tells the PL/SQL runtime engine that package-level data should not persist between references to that data. See Chapter 25, Tuning PL/SQL Applications for more information.
The syntax for using the PRAGMA keyword is as follows:
where <instruction> is a statement providing instructions to the compiler. You would call EXCEPTION_INIT as follows:
DECLARE no_such_sequence EXCEPTION; PRAGMA EXCEPTION_INIT (no_such_sequence, -2289); BEGIN ... END;
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