DATA BASE TRIGGER
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A data base trigger is an Oracle PL/SQL program that resides in the data base. It is only executed (fired) when the event that it is programed for occurs. The firing of the trigger occurs after all the other processing has been performed against the data and just at the moment prior (a BEFORE trigger) or just subsequent (an AFTER trigger) to the data base event. The events may be one or more of: INSERT (adding), UPDATE or DELETE.

If there are multiple triggers that are executed for the same event, there is no means to control which one is executed first (i.e. two BEFORE INSERT triggers - one for referential integrity and one for workflow)

Within the Wiki application, triggers are used as noted:

BEFORE INSERT#

These triggers, identified by a naming convention of P2K_xxx_BRI (where xxx is the table alias) are used to perform the following tasks:

BEFORE UPDATE#

These triggers, identified by a naming convention of P2K_xxx_BRU (where xxx is the table alias) are used to perform the following tasks:

BEFORE DELETE#

These triggers, identified by a naming convention of P2K_xxx_BRD (where xxx is the table alias) are used to perform the following tasks:

LOGGING TRIGGERS#

These triggers are optionally defined and are identified by a naming conventions P2K_xx_LOG_TRG (where xxx is the table alias) are used to extend the audit logging facility within the application to capture changes made externally to the application. The actual trigger fires after the change has been committed to the data base (AFTER INSERT, UPDATE, DELETE). Triggers are created by the am_xmlt.sql script and dropped using the db_drop_logging_triggers.sql script.

WORKFLOW TRIGGERS#

These triggers, identified by a naming convention of P2K_xxx_BIUD (where xxx is the table alias) are used to control the processing of workflow, if defined. The trigger fires after all the data has been manipulated, but just prior to the actual commit to the data base (BEFORE INSERT, UPDATE, DELETE)

CACHING TRIGGERS#

These triggers, identified by a naming convention of P2K_xxx_AIUD (where xxx is the table alias) are used to enable the application server to cache the changes to records. The actual trigger fires after the change has been committed to the data base (AFTER INSERT, UPDATE, DELETE). See the article on caching for further details on how this works. These triggers are created by the db_generate_monitor_triggers.sql script and dropped by the db_drop_monitor_triggers.sql script.