A database trigger is procedural code that is automatically executed in response to certain events on a particular table or view in a database. The trigger is mostly used for maintaining the integrity of the information on the database.
CREATE OR REPLACE TRIGGER [Trigger Name] [Before / After / Instead Of]
Types of PL/SQL triggers :
> Row trigger - The trigger fires for each ROW affected.
> Statement trigger - The trigger is fired once when the condition is matched
> Before and After trigger - The BEFORE trigger run the trigger action before the insert, update or delete statement. The AFTER trigger runs the trigger action after the insert, update or delete statement is executes.