trigger in mysql

1-- The following statement creates an AFTER UPDATE trigger on the sales table:
2
3DELIMITER $$
4
5CREATE TRIGGER after_sales_update
6AFTER UPDATE
7ON sales FOR EACH ROW
8BEGIN
9    IF OLD.quantity <> new.quantity THEN
10        INSERT INTO SalesChanges(salesId,beforeQuantity, afterQuantity)
11        VALUES(old.id, old.quantity, new.quantity);
12    END IF;
13END$$
14
15DELIMITER ;

1CREATE
2    TRIGGER `event_name` BEFORE/AFTER INSERT/UPDATE/DELETE
3    ON `database`.`table`
4    FOR EACH ROW BEGIN
5		-- trigger body
6		-- this code is applied to every 
7		-- inserted/updated/deleted row
8    END;
9    
10CREATE
11	TRIGGER `blog_after_insert` AFTER INSERT 
12	ON `blog` 
13	FOR EACH ROW BEGIN
14	
15		IF NEW.deleted THEN
16			SET @changetype = 'DELETE';
17		ELSE
18			SET @changetype = 'NEW';
19		END IF;
20    
21		INSERT INTO audit (blog_id, changetype) VALUES (NEW.id, @changetype);
22		
23    END$$

1CREATE TRIGGER trigger_name
2{BEFORE | AFTER} {INSERT | UPDATE| DELETE }
3ON table_name FOR EACH ROW
4trigger_body;

1CREATE TRIGGER Product_Details_tr 
2BEFORE INSERT ON Product_Details 
3FOR EACH ROW 
4SET NEW.User_ID = CURRENT_USER();