数据库查询每门课的前两名学号、课程号、成绩
有个课程表,里面有S#(学号)、C#(课程号)、score(成绩)三个字段,现在要选出每门课的前两名,在网上搜到了下面的sql语句,一直看不明白,不知道内外链接的使用,请朋友赐教,说下sql 执行的过程,谢谢!
select sc1.s#,sc1.c#,sc1.score from score sc1 where score in
(select top 2 sc2.score from score sc2
where sc2.C# = sc1.C# order by sc2.score desc)
order by sc1.C# , sc1.score desc