一个简单的SQL语句,送分的,多谢了!

[dawnhorizon]

已知关系模式：
Student(S#学号，Sname姓名，Ssex性别，Sage年龄，Sdept系)，S#为主关键字；
Course（C#课程编号，Cname课程名，Ccredit学分），C#为主关键字；
Sc（S#学号，C#课号，Grade成绩），S#与C#的属性组合为主关键字。
查询Sdept为本系选修了3门以上课程的学生学号，请分别用嵌套查询和连接查询给出答案。

本人刚开始学习SQL,很多地方还不熟,多谢热心人了!

[pengdali]

select s# from sc group by s# having count(*)>=3

[愉快的登山者]

1。嵌套查询：
select A.S# from Sc as A, Student as B
where B.Sdept = ‘本系’
and A.S# = B.S#
and (select count(*) from Sc where S# = A.S#) >= 3
order by A.S#
2。连接查询：
select A.S# from Sc as A left join Student as B
on A.S# = B.S#
where B.Sdept = ‘本系’
and (select count(*) from Sc where S# = A.S#) >= 3
order by A.S#

[yoki]

select s#
from student a
where sdept='系名' and a.s# in
(
select b.s# from sc b group by b.s# having count(*)>=3
)

[happydreamer]

select a.S#
from sc a join student b on a.s#=b.s#
where b.sdept='本系' and (select count(c#) from sc where s#=a.s#)>=3