Triggers

See Also   Tasks

A trigger is a special kind of stored procedure that goes into effect when you modify data in a specified table using one or more data modification operations: UPDATE, INSERT, or DELETE. Triggers can query other tables and can include complex SQL statements. They are primarily useful for enforcing complex business rules or requirements. For example, you could control whether to allow an order to be inserted based on a customer's current account status.

Triggers are also useful for enforcing referential integrity, which preserves the defined relationships between tables when you add, update, or delete the rows in those tables. However, the best way to enforce referential integrity is to define primary key and foreign key constraints in the related tables. If you use database diagrams, you can create a relationship between tables to automatically create a foreign key constraint. For details, see Table Relationships.

Advantages of Using Triggers

Triggers are useful in these ways:

For details about working with triggers, see the following topics:

To See
Create new triggers Creating a Trigger
Open existing triggers Opening a Trigger
Save triggers to your project Saving a Trigger
Change the name of a trigger Renaming a Trigger
Delete stored triggers Deleting a Trigger