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TRIGGER_BEFORE_UPDATE

A TRIGGER_BEFORE_UPDATE program is a program that you create and that Oracle OLAP checks for by name when an UPDATE statement executes. When the program exists in the same analytic workspace that you are updating, Oracle OLAP executes the program and then, depending on the value returned by the program (if any), either does nor does not update the workspace.

Note: The USETRIGGERS option must be set to its default value of TRUE for a TRIGGER_BEFORE_UPDATE program to execute

See also: A TRIGGER_BEFORE_UPDATE program is only one of a number of trigger programs that you can write. You can write other trigger programs as described in TRIGGER command, TRIGGER_AFTER_UPDATE, TRIGGER_DEFINE, and "Trigger Programs".

Return Value

You can write the program as a function that returns a BOOLEAN value. In this case, when the program returns FALSE, Oracle OLAP does not execute the UPDATE statement that triggered the execution of the TRIGGER_BEFORE_UPDATE program; when the program returns TRUE or NA, the UPDATE statement executes.

Notes

No Support for Recursive Triggers

Oracle OLAP does not support recursive triggers. You must set the USETRIGGERS option to NO before you issue an UPDATE statement within a TRIGGER_BEFORE_UPDATE program.

Syntax

To create a program with the name TRIGGER_UPDATE, follow the guidelines presented in"Trigger Programs".

Examples

Example 24-12 TRIGGER_BEFORE_UPDATE Program

Assume that an analytic workspace named myaw has an TRIGGER_BEFORE_UPDATE program with the following definition.

DEFINE TRIGGER_BEFORE_UPDATE PROGRAM BOOLEAN
PROGRAM
SHOW JOINCHARS ('calltype = ' CALLTYPE)
SHOW JOINCHARS ('triggering event = ' TRIGGER(EVENT))
SHOW JOINCHARS ('triggering subevent = ' TRIGGER(SUBEVENT))
RETURN TRUE
END
 

Assume that you define a TEXT variable named myvar and, then, issue an UPDATE statement. The TRIGGER_BEFORE_UPDSATE program executes.

calltype = TRIGGER
triggering event = BEFORE_UPDATE
triggering subevent = AW

Because the program returned TRUE, the definition for myvar exists after you detach and reattach the workspace.

AW DETACH myaw
AW ATTACH myaw
DESCRIBE

DEFINE TRIGGER_BEFORE_UPDATE PROGRAM BOOLEAN
PROGRAM
SHOW JOINCHARS ('calltype = ' CALLTYPE)
SHOW JOINCHARS ('triggering event = ' TRIGGER(EVENT))
SHOW JOINCHARS ('triggering subevent = ' TRIGGER(SUBEVENT))
RETURN TRUE
END
 
DEFINE MYVAR VARIABLE TEXT

However, if you modified the program so that it returned FALSE, then when you detach and reattach the workspace, not only would the myvar definition not in the workspace, the definition for the TRIGGER_BEFORE_UPDATE program would also not be in the workspace.