Using EXCEPTION_INIT

To handle unnamed internal exceptions, you should use the OTHERS handler or the pragma EXCEPTION_INIT. The pragma is a compiler directive that can be thought of as a parenthetical comment to the compiler. The Pragmas (also known as the pseudoinstructions) are processed at the compile time, not at run time. For illustration, in the language Ada, the pragma below tells the compiler to optimize the use of the storage space:

pragma OPTIMIZE(SPACE);

In the PL/SQL, the pragma EXCEPTION_INIT tells the compiler to relate an exception name with an Oracle error number. This permits you to refer to any internal exception by name & to write a specific handler for it. In the declarative section of a PL/SQL subprogram, block, or package you can code the pragma EXCEPTION_INIT using the syntax as shown:

PRAGMA EXCEPTION_INIT(exception_name, Oracle_error_number);

Where the exception_name is the name of an earlier declared exception. The pragma should appear anywhere after the exception declaration in the similar declarative part, as shown in the illustration below:

DECLARE

deadlock_detected EXCEPTION;

PRAGMA EXCEPTION_INIT(deadlock_detected, -60);

BEGIN

...

EXCEPTION

WHEN deadlock_detected THEN

-- handle the error

END;