Chapter 30. Tiggers

Atrigger defines an action the database should take when some database-related event occurs. Triggers may be used to supplement declarative referential integrity, to enforce complex business rules, or to audit changes to data. The code within a trigger, called the trigger body, is made up of PL/SQL blocks (see Chapter 29).

The execution of triggers is transparent to the user. Triggers are executed by the database when specific types of data manipulation commands are performed on specific tables. Such commands may include inserts, updates, and deletes. Updates of specific columns may also be used as triggering events. Triggering events may also include DDL commands and database events such as shutdowns and logins.