select * from S where exists( select 1 from C where not exists (select 1 from SC where C.C#=C# and SC.S#=S.S# ))
这句得到的结果是没有选择全部课程的学生

select * from s where s#=(select s# from sc group by s# having count(*)=(select count(*) from c))

还是比较习惯最后一句．

我也写了一个 好象也没出现错误 大家多多指教
select SN,SD FROM S
WHERE S.S#
IN(
SELECT SC.S# FROM SC
GROUP BY SC.S#
HAVING COUNT(*) =(SELECT COUNT(C#) FROM C)
)

谢谢大家了!我也正需要这个呢!

大家是不是可以再加几个要求,多举几个例子呢!谢谢了!

看看这句：完全正确，符合要求。
SELECT S#,SD FROM S WHERE NOT EXISTS
(SELECT C# FROM C WHERE NOT EXISTS
(SELECT C# FROM SC WHERE S.S#=SC.S# AND C.C#=SC.C#)
)

哇～～

太好了，我也在学