标签：code HERE creat end row val delete values tab
触发器：监视某种情况，并触发某种操作
触发器创建语法四要素：1、监视地点(TABLE)
2、监视事件（INSERT/UPDATE/DELETE）
3、触发时间(AFTER/BEFORE)
4、触发事件(INSERT/UPDATE/DELETE)
触发器--INSERT事件
INSERT INTO order_table(gid,much) VALUES(1,3); CREATE TRIGGER tg1 AFTER INSERT ON order_table FOR EACH ROW BEGIN UPDATE goods SET num=num-new.much WHERE id=new.gid; END
触发器--UPDATE事件
UPDATE order_table SET much=much-2 WHERE oid=11; CREATE TRIGGER tg2 AFTER UPDATE ON order_table FOR EACH ROW BEGIN UPDATE goods SET num=num+old.much-new.much WHERE id=old.gid; END
触发器--DELETE事件
DELETE FROM order_table WHERE oid=11; UPDATE goods SET num=num+1 WHERE id=1; CREATE TRIGGER tg3 AFTER DELETE ON order_table FOR EACH ROW BEGIN UPDATE goods SET num=num+old.much WHERE id=old.gid; END
标签：code HERE creat end row val delete values tab
原文地址：https://www.cnblogs.com/start20180703/p/10353125.html
