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About database triggers

Database triggers are procedures that are stored in the database and implicitly executed when a triggering statement such as INSERT, UPDATE, or DELETE is issued against the associated table. Triggers can be defined only on tables, not on views. However, triggers on the base table of a view are fired if an INSERT, UPDATE, or DELETE statement is issued against a view.

A trigger can include SQL and PL/SQL statements that execute as a unit, and can invoke other stored procedures. Use triggers only when necessary. Excessive use of triggers can result in cascading or recursive triggers. For example, when a trigger is fired, a SQL statement in the trigger body potentially can fire other triggers.

By using database triggers, you can enforce complex business rules and ensure that all applications behave in a uniform manner. Use the following guidelines when designing triggers:

For additional information about how triggers are used in applications, see the Oracle Application Developer's Guide. See the Oracle Concepts Manual for more information about the different types of triggers.

See also

About triggers

Creating a database trigger