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Exception handling
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The common syntax rules for EXCEPTION statement is:

EXCEPTION [[name] [value]];


Run-time exception messages (FB 1.5)
------------------------------------

Function:
Allows to throw exceptions with text message
defined at runtime.

Author:
Dmitry Yemanov <yemanov@yandex.ru>

Syntax rules:
EXCEPTION <exception_name> <message_value>;

Scope:
PSQL

Example(s):
1. EXCEPTION E_EXCEPTION_1 'Error!';
2. EXCEPTION E_EXCEPTION_2 'Wrong type for record with ID=' || new.ID;


Exception re-raise semantics (FB 1.5)
-------------------------------------

Function:
Allows to re-initiate catched exception.

Author:
Digitman <digitman@hotbox.ru>

Syntax rules:
EXCEPTION;

Scope:
PSQL, context of the exception handling block

Example(s):
BEGIN
...
WHEN SQLCODE -802 DO
EXCEPTION E_ARITH_EXCEPT;
WHEN SQLCODE -802 DO
EXCEPTION E_KEY_VIOLATION;
WHEN ANY DO
EXCEPTION;
END

Note(s):
Evaluates to no-op if used outside the exception handling block.


Run-time error codes (FB 1.5)
-----------------------------

Function:
Allows to get a numeric error code for the catched exception.

Author:
Dmitry Yemanov <yemanov@yandex.ru>

Syntax rules:
SQLCODE / GDSCODE;

Scope:
PSQL, context of the exception handling block

See also:
README.context_variables