------------------ Exception handling ------------------ 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. Parameterized exceptions (FB 3.0) --------------------------------- Function: Allow to define exception message with slots for parameters and pass the parameters when raising the exception. Author: Adriano dos Santos Fernandes <adrianosf at gmail.com> Syntax: EXCEPTION <name> USING ( <value list> ) Example: create exception e_invalid_val 'Invalid value @1 for the field @2'; ... if (val < 1000) then thing = val; else exception e_invalid_val using (val, 'thing'); end Notes: The maximum number of arguments passed is 9. In the exception message, @NN (example: @10) is considered as @1 followed by the literal 0. The status vector is generated using these codes combination: isc_except, <exception number>, isc_formatted_exception, <formatted exception message>, <exception parameters> Since new error code (isc_formatted_exception) is used, it's necessary that the client is v3.0 or at least uses firebird.msg from v3.0 so that it can translate the status vector to string. @N means the N parameter (where N starts at 1) passed in the exception raise command. If a N parameter is not passed, the text is not substituted. If NULL is passed, it's replaced by string '*** null ***'. If more parameters are passed than used in the exception message, they are ignored.