处用MYSQL，麻烦大家帮我看看这个简单的触发器问题

[Z8157522]

用的MYSQL 5.0
想吧表中某值的旧值和新值差加到另一张表中的某个字段中去。//这一步还没写到，麻烦有心人给个提示
但是写触发器的时候总是报错。不知道为什么。请大家帮忙看看。
一下两段代码都只是先写出来做下测试的，但是有问题。

CREATE TRIGGER update_position
AFTER UPDATE on position_tb FOR EACH ROW
BEGIN
IF (NEW.score <> OLD.score) THEN SELECT * FROM position_tb;
ELSE
SELECT * FROM class_tb;
END IF;
END;

错误：
Error Code : 1064
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT * FROM position_tb' at line 4
(0 ms taken)

Error Code : 1064
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ELSE
SELECT * FROM class_tb' at line 1
(0 ms taken)

Error Code : 1064
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'END IF' at line 1
(0 ms taken)

Error Code : 1064
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'END' at line 1
(0 ms taken)

CREATE TRIGGER update_position
AFTER UPDATE on position_tb FOR EACH ROW
BEGIN
select * from position_tb;
END;

错误：
Error Code : 1064
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'select * from position_tb' at line 4
(0 ms taken)

Error Code : 1064
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'END' at line 1
(0 ms taken)

[wwwwb]

你要达到什么目的？

[wwwwb]

CREATE TRIGGER update_position
AFTER UPDATE on position_tb FOR EACH ROW
BEGIN
IF (NEW.score <> OLD.score) THEN
insert into position_tb SELECT *,NEW.score -OLD.score FROM position_tb;
ELSE
insert into position_tb SELECT * FROM class_tb;
END IF;
END;

[Z8157522]

是把这个差值，与另一个表,比如personalinfo表中的score字段相加。

能告诉我我之前那样写的语句为什么会报错吗？

[zuoxingyu]

首先把语法弄清楚。然后多动手测试，实在不行再来问。

[Z8157522]

比如说我在这张表（position_tb）中有一个人员ID和score字段，当该表score字段更新值的时候,同时把差值加到另一张表（personalinfo_tb）表的level字段上。

[ACMAIN_CHM]

看一下手册中的基础教程部分。

MySQL官方文档 http://dev.mysql.com/doc/refman/5.1/zh/index.html