What is trigger timing?

What is trigger timing?

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When defining a trigger, the trigger timing (whether the trigger action is to be executed before or after the triggering statement) can also be specified by using the BEFORE or AFTER option respectively. The BEFORE and AFTER options apply to both statement and row triggers. Hence, by using the BEFORE and AFTER options, the following four types of row and statement triggers can be created:

1. BEFORE statement trigger: This trigger executes the trigger action before the triggering statement is executed.


2. BEFORE row trigger: This trigger executes the trigger action once for each affected row before the triggering statement is executed and integrity constraints are applied, provided the trigger restriction is not violated.


3. AFTER statement trigger: This trigger executes the trigger action after the triggering statement is executed and integrity constraints, if any, are applied.


4. AFTER row trigger: This trigger executes the trigger action once for each affected row after the triggering statement is executed and integrity constraints are applied, provided the trigger restriction is not violated. Unlike the BEFORE row triggers, the AFTER row triggers lock rows.

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