Introduction to SQL Triggers

What Are SQL Triggers?

A trigger is a special kind of stored procedure that runs automatically when certain events occur in the database.

These events typically include INSERT, UPDATE, or DELETE operations on a table or view.

• Triggers are bound to a specific table or view.
• They execute automatically without explicit calls from users or applications.
• Triggers can enforce complex business rules at the database level.

Types of SQL Triggers

Triggers can be classified based on when they execute relative to the triggering event.

• BEFORE triggers run before the data modification occurs.
• AFTER triggers run after the data modification is completed.
• INSTEAD OF triggers replace the triggering operation, commonly used with views.

Basic Syntax of SQL Triggers

The syntax for creating a trigger varies slightly between database systems but generally follows a similar pattern.

Here is a generic example of creating an AFTER INSERT trigger.