A trigger is a special types of stored procedure that automatically runs when a language event execute We can say that an action causing the automatic invocation of a procedure, for instance to preserve {referential integrity}. A triggers goes into effect when a user attempts to modify data with an insert, delete, or update command. A trigger can instruct the system to take any number of actions when a specified change is attempted.

Triggers are basically used to implement business rules. Triggers is also similar to stored procedures. The difference is that it can be activated when data is added or edited or deleted from a table in a database.