50个查询系列-第8个查询：查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名；

做法：

select tblstudent.StuId,tblstudent.StuName from tblstudent where
(
(select tblscore.Score from tblscore where tblstudent.StuId=tblscore.StuId and tblscore.CourseId=‘002‘)
<(select tblscore.Score from tblscore where tblstudent.StuId=tblscore.StuId and tblscore.CourseId=‘001‘)
)

文章来自：http://www.cnblogs.com/shenxiaoquan/p/6120207.html