What is Trigger

SQL create trigger statement provides a way for the database management system to actively controls and monitor and manage the group of table when ever an update the data or delete the data or insert the data in that time performed.Trigger excuted each time an sql insert,update,delete operation is performed.

create trigger tri_update on Empfor update
as
begin
if update(EmpID)
begin
print'not update here'rollback transactionendend
update Emp set EmpID='jj' where UserName='mahagr'
-------output:------
not update hereMsg 3609,
Level 16, State 1, Line 1
The transaction ended in the trigger. The batch has been aborted.
different types of triggers:-
Row Triggers and Statement Triggers BEFORE and AFTER Triggers INSTEAD OF Triggers Triggers on System Events and User Events