我这样写查询语句为什么错？

[wangjinbao]

INSERT INTO course1 ( studentno, coursechenji, activechenji, studychenji )
SELECT studentno, sum(coursechenji), sum(activechenji), sum(studychenji)
FROM course_chenji, active_chenji, study_chenji
WHERE course_chenji.studentno=active_chenji.studentno and active_chenji.studentno=studychenji.studentno
GROUP BY studentno;

[jackting]

INSERT INTO course1 ( studentno, coursechenji, activechenji, studychenji )
SELECT a.studentno, sum(a.coursechenji), sum(b.activechenji), sum(c.studychenji)
FROM course_chenji a, active_chenji b, study_chenji c
WHERE a.studentno*=b.studentno
and a.studentno*=c.studentno
GROUP BY a.studentno

[pbsql]

列名前均需加上表名，如：course_chenji.studentno

[wangjinbao]

a.studentno*=b.studentno and a.studentno*=c.studentno后面加入*号是什么意思

[wychero]

首先你查询的几个表当中都有 Student 这个字段，你在 Select 和 Group 时没有指明表名。
a.studentno*=b.studentno 是表示左连接，相当于 Left Join ，详情请查帮助。