mysql问题

1有 关系模式：User（userId, userName）， Article（articleId, userId, title, content），Vote（articleId, score），User为用户关系，Article为用户发表的文章关系，Vote为文章得票关系，title为文章标题、score为得票数。 （1）用SQL语言查询出发表文章数大于5，文章平均得票数大于100的用户名，按平均得票数倒序排列； select dd.userName from (select User.userName as userName,aa.userId as userId from User,(select userId,count(*) as ant from Article group by userId)as aa where User.userId = aa.userId and aa.ant >5) as dd,(select Article.userId as userId, avg(Vote.score) as avg from Vote,Article where Article.articleId=Vote.articleId group by Article.userId) as cc where dd.userId = cc.userId and cc.avg>100 order by cc.avg desc;