A trigger is a special type of stored procedure that automatically runs when an event occurs in the database server. They are commonly used for automated audit trails and logging.
SQL Triggers
Execute SQL automatically in response to INSERT, UPDATE, or DELETE events.
Key Takeaways: SQL Triggers
Mastering SQL Triggers helps you write clean and reliable SQL code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.
SQL Triggers Code Example
SQLCREATE TRIGGER audit_price_update
AFTER UPDATE ON products
FOR EACH ROW
BEGIN
IF OLD.price <> NEW.price THEN
INSERT INTO price_audit (product_id, old_price, new_price, changed_at)
VALUES (NEW.id, OLD.price, NEW.price, NOW());
END IF;
END;Output
Automates audit history logging on product price changes
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