Home >> FAQs/Tutorials >> SQL Server FAQ

SQL Server FAQ - What Are Triggers

By: FYIcenter.com

(Continued from previous topic...)

What Are Triggers?

A trigger is a special kind of stored procedure that automatically executes when an event occurs in the database server. A trigger is really an event handler. SQL Server allows users to create triggers (event handlers) for 3 types of events:

• DML Event - Occurs when a DML (Data Manipulation Language) statement: INSERT, UPDATE or DELETE, is executed.
• DDL Event - Occurs when a DDL (Data Definition Language) statement: CREATE, ALTER, or DROP, is executed.
• Logon Event - Occurs when a user logins to the Server.

There are 3 different types of triggers (event handlers) based on the types of events they are triggered by:

• DML Trigger - Executes in response to a DML event.
• DDL Trigger - Executes in response to a DDL event.
• Logon Trigger - Executes in response to a logon event.

(Continued on next topic...)

1. What Are Triggers?
2. What Are the Basic Features of a Trigger?
3. How To Create a Simple Table to Test Triggers?
4. How To Create a DML Trigger using CREATE TRIGGER Statements?
5. How To Test a DML Trigger?
6. How To List All Triggers in the Database with sys.triggers?
7. How To Modify Existing Triggers using "ALTER TRIGGER"?
8. How To Delete Existing Triggers using "DROP TRIGGER"?
9. How To Get the Definition of a Trigger Back?
10. How To Disable Triggers using "DISABLE TRIGGER"?
11. How To Create a Trigger for INSERT Only?
12. How To See the Event List of an Existing Trigger using sys.trigger_events?
13. How To Access the Inserted Record of an Event?
14. How To Access the Deleted Record of an Event?
15. How To Improve the Trigger to Handle NULL Values?
16. What Happens to a Trigger with Multiple Affected Rows?
17. How To Override DML Statements with Triggers?
18. How To Create a DDL Trigger using "CREATE TRIGGER" Statements?
19. Can You Roll Back the DDL Statement in a Trigger?
20. Can You Create a Logon Trigger in SQL Server 2005 Express Edition?