A trigger is a special kind of stored procedure that is invoked whenever an attempt is made to modify the data in the table it protects. Modifications to the table are made ussing INSERT,UPDATE,OR DELETE statements.
Triggers are used to enforce data integrity and business rules such as automatically updating summary data. It allows to perform cascading delete or update operations. If constraints exist on the trigger table,they are checked prior to the trigger execution. If constraints are violated statement will not be executed and trigger will not run.Triggers are associated with tables and they are automatic . Triggers are automatically invoked by SQL SERVER. Triggers prevent incorrect , unauthorized,or inconsistent changes to data.
