There are various advantages of using a trigger. Some of them are:
- Suppose we need to validate a DML statement(insert/Update/Delete) that modifies a table then we can write a trigger on the table that gets fired implicitly whenever DML statement is executed on that table.
- Another reason of using triggers can be for automatic updation of one or more tables whenever a DML/DDL statement is executed for the table on which the trigger is created.
- Triggers can be used to enforce constraints. For eg : Any insert/update/ Delete statements should not be allowed on a particular table after office hours. For enforcing this constraint Triggers should be used.
- Triggers can be used to publish information about database events to subscribers. Database event can be a system event like Database startup or shutdown or it can be a user even like User loggin in or user logoff.