select a.cid,cname,max(a.score)"最高分",min(a.score)“最低分”,avg(a.score)"平均分",((select count(sid) from SC where score>=60 and cid=b.cid )/(select count(sid) from SC where cid=b.cid)) "及格率"from SC ainner join Course b on a.cid = b.cidgroup by b.cid;
Student表:
SC表:
Teacher表:
Course表:
18.查询各科成绩最高分 最低分和平均分:以如下形式显示:课程ID 课程name 最高分 最低分 平均分 及格率