Question

If the values in an SQL view are not changeable through the view itself, you may still be able to update the view by using unique application logic. In this case, the specific logic is placed in an INSTEAD OF trigger. What is the purpose of an INSTEAD OF trigger in SQL?

1) To prevent any changes to the view
2) To allow changes to the view
3) To update the view automatically
4) To execute a specific logic when changes are made to the view

Answer 1

An INSTEAD OF trigger allows the execution of custom logic when a user tries to insert, update, or delete data in an SQL view that is not directly updatable. It performs the necessary data manipulation on the underlying tables in a way that reflects the operation intended on the view.

Step-by-step explanation:

The purpose of an INSTEAD OF trigger in SQL is to execute specific logic when changes are made to a view or table that cannot be modified directly. When an attempt is made to insert, update, or delete data in a view (which normally does not support these actions if the view is based on multiple tables or includes aggregates, for instance), the INSTEAD OF trigger fires and runs the code defined inside it. This code typically then performs the necessary insert, update, or delete actions on the underlying tables directly, in a way that is consistent with the intent of the operation on the view. Therefore, the correct answer to the student's question is 4) To execute a specific logic when changes are made to the view.