题目：按照课程号进行分组，统计学生平均成绩大于60分的学生的信息( )
select cid,avg(grade) from student where avg(grade)>60 group by cid
select cid,avg(grade) from student group by cid having avg(grade)>60
select cid,avg(grade) from course where avg(grade)>60 group by cid
select cid,avg(grade) from sc group by cid having avg(grade)>60
