Trigger In Database Trigger Event, Trigger Restriction, Trigger Action Explain

How To Apply Triggers In Database Management, Apply Trigger In Database Explain, What Is Trigger Event, Restriction, Action Explain, Parts Of Trigger In DBMS

How to apply database trigger

A trigger has three basic parts

A triggering event or statement
It is a SQL statement that causes a trigger to be fired.
It can be INSERT, UPDATE or DELETE statement for a specific table.


A trigger restriction
A trigger restriction specifies a Boolean (logical) expression that must be TRUE for the trigger to fire.
It is an option available for triggers that are fired for each row.
Its function is to conditionally control the execution of a trigger.
A trigger restriction is specified using a WHEN clause.



A trigger action
A trigger action is the PL/SQL code to be executed when a triggering statement is encountered and any trigger restriction evaluates to TRUE.
The PL/SQL block can contain SQL and PL/SQL statements, can define PL/SQL language constructs and can call stored procedures.

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