Trigger in pl/sql

Hi Jimmy,

Trigger is like a stored procedure that are ran automatically by the database when ever an event occurs.It may be BEFORE or AFTER.

Triggers are fired implicitly on the tables/views on which they are created. 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.

Refer

http://docs.oracle.com/cd/B28359_01/server.111/b28318/triggers.htm

Thanks

1 Reply

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Satyapriya Nayak14y ago
Hi Jimmy,

Trigger is like a stored procedure that are ran automatically by the database when ever an event occurs.It may be BEFORE or AFTER.

Triggers are fired implicitly on the tables/views on which they are created. 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.

Refer

http://docs.oracle.com/cd/B28359_01/server.111/b28318/triggers.htm

Thanks