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100 lines
2.4 KiB
Plaintext
100 lines
2.4 KiB
Plaintext
------------------
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Exception handling
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------------------
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The common syntax rules for EXCEPTION statement is:
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EXCEPTION [[name] [value]];
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Run-time exception messages (FB 1.5)
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------------------------------------
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Function:
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Allows to throw exceptions with text message
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defined at runtime.
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Author:
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Dmitry Yemanov <yemanov@yandex.ru>
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Syntax rules:
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EXCEPTION <exception_name> <message_value>;
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Scope:
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PSQL
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Example(s):
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1. EXCEPTION E_EXCEPTION_1 'Error!';
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2. EXCEPTION E_EXCEPTION_2 'Wrong type for record with ID=' || new.ID;
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Exception re-raise semantics (FB 1.5)
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-------------------------------------
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Function:
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Allows to re-initiate catched exception.
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Author:
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Digitman <digitman@hotbox.ru>
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Syntax rules:
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EXCEPTION;
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Scope:
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PSQL, context of the exception handling block
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Example(s):
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BEGIN
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...
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WHEN SQLCODE -802 DO
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EXCEPTION E_ARITH_EXCEPT;
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WHEN SQLCODE -802 DO
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EXCEPTION E_KEY_VIOLATION;
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WHEN ANY DO
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EXCEPTION;
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END
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Note(s):
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Evaluates to no-op if used outside the exception handling block.
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Parameterized exceptions (FB 3.0)
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---------------------------------
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Function:
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Allow to define exception message with slots for parameters and pass the parameters when
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raising the exception.
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Author:
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Adriano dos Santos Fernandes <adrianosf at gmail.com>
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Syntax:
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EXCEPTION <name> USING ( <value list> )
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Example:
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create exception e_invalid_val 'Invalid value @1 for the field @2';
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...
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if (val < 1000) then
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thing = val;
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else
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exception e_invalid_val using (val, 'thing');
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end
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Notes:
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The maximum number of arguments passed is 9.
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In the exception message, @NN (example: @10) is considered as @1 followed by the literal 0.
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The status vector is generated using these codes combination:
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isc_except, <exception number>,
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isc_formatted_exception, <formatted exception message>, <exception parameters>
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Since new error code (isc_formatted_exception) is used, it's necessary that the client is v3.0
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or at least uses firebird.msg from v3.0 so that it can translate the status vector to string.
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@N means the N parameter (where N starts at 1) passed in the exception raise command. If a N
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parameter is not passed, the text is not substituted. If NULL is passed, it's replaced by string
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'*** null ***'. If more parameters are passed than used in the exception message, they are
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ignored.
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