CREATE TABLE `demo_1` (
 `ID` int(11) NOT NULL AUTO_INCREMENT COMMENT '主键',
 `STUNAME` varchar(32) DEFAULT NULL COMMENT '名字',
 `AGE` tinyint(4) DEFAULT NULL COMMENT '年龄',
 PRIMARY KEY (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=14 DEFAULT CHARSET=utf8;

CREATE TABLE `demo_2` (
 `ID` int(11) NOT NULL AUTO_INCREMENT COMMENT '主键',
 `STU_ID` int(11) DEFAULT NULL COMMENT '学生编号',
 `MATH` double DEFAULT NULL COMMENT '成绩',
 PRIMARY KEY (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8;

DROP TRIGGER IF EXISTS `insertTragger`;
DELIMITER ;;
CREATE TRIGGER `insertTragger` AFTER INSERT ON `demo_1` FOR EACH ROW begin
select ID INTO @v1 from demo_1 order by ID desc limit 1;
Insert into demo_2(STU_ID, MATH) values(@v1, 98.5);
end
;;
DELIMITER ;

DROP TRIGGER IF EXISTS `insertTragger`;
DELIMITER ;;
CREATE TRIGGER `insertTragger` AFTER INSERT ON `demo_1` FOR EACH ROW begin
if @enable_trigger = 1 then
select ID INTO @v1 from demo_1 order by ID desc limit 1;
Insert into demo_2(STU_ID, MATH) values(@v1, 98.5);
end if;
end
;;
DELIMITER ;

SET @enable_trigger = 1;
INSERT INTO demo_1(STUNAME , AGE) VALUES(‘小强', 17);
执行之后，表demo_1中增加一条数据
2 小强 17
表demo_2中同样也增加一条数据
2 2 98.5

SET @enable_trigger = 0;
INSERT INTO demo_1(STUNAME , AGE) VALUES(‘小强', 17);
执行之后：
执行之后，表demo_1中增加一条数据
2 小强 17