MYSQL 触发器

Posted 2020-12-01 一只小白呀

#触发器

#创建基本语法

#插入前
CREATE trigger tri_before_insert_tb1 BEFORE INSERT ON tb1 FOR EACH ROW
BEGIN 
...
END

#插入后

CREATE TRIGGER tri_after_insert_tb1 AFTER INSERT ON tb1 FOR EACH ROW
BEGIN
...
END 

#删除前
CREATE TRIGGER tri_before_delete_tb1 BEFORE DELETE tb1 FOR EACH ROW
BEGIN 
...
END 

#删除后
CREATE TRIGGER tri_after_delete_tb1 AFTER DELETE tb1 FOR EACH ROW
BEGIN 
...
END 

#更新前
CREATE TRIGGER tri_beofre_update_tb1 BEFORE UPDATE ON tb1 FOR EACH ROW
BEGIN
...
END 

#更新后
CREATE TRIGGER tri_after_update_tb1 AFTER UPDATE ON tb1 FOR EACH ROW
BEGIN
...
END

#插入前触发器
delimiter //
CREATE TRIGGER tri_before_insert_tb1 BEFORE INSERT ON tb1 FOR EACH ROW
BEGIN 
IF NEW.NAME == ‘alex‘ THEN
VAlUES
(‘aa‘)
END 
END // 
delimiter;

 

#插入后触发器
delimiter // 
CREATE TRIGGER tri_before_insert_tb1 AFTER INSERT ON tb1 FOR EACH ROW
BEGIN 
IF NEW.num = 666 THEN 
INSERT INTO tb2 (NAME)
VAlUES
(‘666‘),
(‘666‘);
ELSE IF NEW.num = 555 THEN
INSERT INTO tb2 (NAME)
VAlUES
(‘555‘),
(‘555‘);
END IF;
END//
delimiter;

#删除触发器
DROP TRIGGER tri_after_insert_tb1;

#使用触发器
insert into tb1(num) values(666);