MySql触发器

1.添加事件

DELIMITER $
DROP TRIGGER IF EXISTS m_add_up_customer_num;
create trigger m_add_up_customer_num after insert
on me_table for each row
begin

UPDATE customer SET num = num + 1 WHERE customer_id = new.customer_id;

end$
DELIMITER ; 

2.修改事件

DELIMITER $
DROP TRIGGER IF EXISTS m_up_update_customer_num;
create trigger m_up_update_customer_num after update
on me_table for each row
begin

IF new.is = -1
THEN

UPDATE customer SET num = num - 1 WHERE customer_id = new.customer_id;

END IF;
end$
DELIMITER ;

3.删除事件

DELIMITER $
DROP TRIGGER IF EXISTS m_del_update_customer_num;
create trigger m_del_update_customer_num after DELETE
on me_table for each row
begin

IF  old.is = 1
THEN

UPDATE customer SET num = num - 1 WHERE customer_id = old.customer_id;

END IF;

end$
DELIMITER ;