ENABLE Trigger - (Oracle Advance)

In Oracle database, a trigger is a stored program that is executed automatically in response to an event such as an INSERT, UPDATE, or DELETE operation. By default, triggers are created in a DISABLED state. In order to enable a trigger, the ENABLE keyword is used.

Syntax

The syntax for enabling a trigger in Oracle database is as follows:

ALTER TRIGGER trigger_name ENABLE;

Here, trigger_name is the name of the trigger that you want to enable.

Example

Let's say we have a trigger called employee_salary which is executed after an update operation on the employee table. The trigger updates the salary column in the employee table based on the new salary and commission values.

To enable the trigger, we can use the following command:

ALTER TRIGGER employee_salary ENABLE;

Output

The output of the ENABLE statement is a confirmation message that the trigger has been enabled.

Explanation

In the above example, we have enabled the employee_salary trigger by using the ALTER TRIGGER statement with the ENABLE keyword. This means that the trigger will now be executed automatically in response to an update operation on the employee table.

Use

Enabling a trigger is useful when you want to activate the trigger again after disabling it temporarily. For example, you may want to disable a trigger for a short period of time while you make some changes to the trigger or perform some maintenance on the table. Once you're done, you can enable the trigger again using the ENABLE keyword.

Important Points

• Triggers in Oracle database are stored programs that are executed automatically in response to an event.
• By default, triggers are created in a DISABLED state.
• To enable a trigger, use the ALTER TRIGGER statement with the ENABLE keyword.
• Enabling a trigger is useful when you want to activate the trigger again after disabling it temporarily.

Summary

In summary, enabling a trigger in Oracle database is done using the ALTER TRIGGER statement with the ENABLE keyword. This is useful when you want to activate the trigger again after disabling it temporarily. Triggers are stored programs that are executed automatically in response to an event, and are created in a DISABLED state by default.