Trigger: Trigger is set of statements or stored program which include sql and pl/sql which will be automatucally executed when a specific event happened .It is useful in maintaing the data integrity.This is similar to a stored procedure.Usually we will call the stored procedure explicity through the code of our application.But we wont call triggers explicitly,it will be invoked by the oracle implicitly.These triggers will invoke the stored procedures when an event occurs. like when performing and Data manupulation operations,when executing and DDL operations or during the database events such as log off,login,shutdown. If we wrote a trigger which will be called when a particular type of operation is happened on paticular table.Like If any insert operation is performed,if any update operaation is performed,or if any deleted operation is performed on particular table then automatically the oracle will implicitly call the trigger.Collectively we can say when any DML operations happened . Triggers can be invoked, when a particular user performed any INSERT or ALTER operations Similarly triggers will invoked when any database events happens like logon,logoff,startup and shutdown. Solution Trigger: Trigger is set of statements or stored program which include sql and pl/sql which will be automatucally executed when a specific event happened .It is useful in maintaing the data integrity.This is similar to a stored procedure.Usually we will call the stored procedure explicity through the code of our application.But we wont call triggers explicitly,it will be invoked by the oracle implicitly.These triggers will invoke the stored procedures when an event occurs. like when performing and Data manupulation operations,when executing and DDL operations or during the database events such as log off,login,shutdown. If we wrote a trigger which will be called when a particular type of operation is happened on paticular table.Like If any insert operation is performed,if any update operaation is performed,or if any deleted operation is performed on particular table then automatically the oracle will implicitly call the trigger.Collectively we can say when any DML operations happened . Triggers can be invoked, when a particular user performed any INSERT or ALTER operations Similarly triggers will invoked when any database events happens like logon,logoff,startup and shutdown..