mysql查询(六)
查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩
总数:count() 总分:sum() 排序:ORDER BY 分组:group by
命令:SELECT DISTINCT a.Sid,a.Sname,a.Sage,a.Ssex,b.Cid,b.score from ex_xueshengbiao_95 a
left join (select Sid,count(1) as 'Cid',sum(score) as 'score' from ex_chengjibiao_95 group by sid) b
on a.Sid=b.Sid ORDER BY a.Sid