有一个sql语句如下
select avg(grade)from score where score.id in (select student.id from student where clazz='10网络2')group by score.id
这样写能查到平均分,但要改成下面这样就有有异常:
select score.id avg(grade)from score where score.id in (select student.id from student where clazz='10网络2')group by score.id
就加了个score.id就不行了,这是什么原因,该怎么解决?急急急,求大侠帮帮忙
select avg(grade)from score where score.id in (select student.id from student where clazz='10网络2')group by score.id
这样写能查到平均分,但要改成下面这样就有有异常:
select score.id avg(grade)from score where score.id in (select student.id from student where clazz='10网络2')group by score.id
就加了个score.id就不行了,这是什么原因,该怎么解决?急急急,求大侠帮帮忙
没逗号 score.id 后面加逗号select score.id ,avg(grade)from score where score.id in (select student.id from student where clazz='10网络2')group by score.id
select A.id,avg(A.grade)
from score A, student B
where A.id=B.id and B.clazz='10网络2'
group by A.id
select score.id,avg(grade)from score where score.id in (select student.id from student where clazz='10网络2')group by score.id select score.id avg(grade)from score
inner join student on score.id=student.id
where studen.clazz='10网络2' group by score.id