数据库中有三个关系,求SQL语句

[yanqlv]

数据库中有三个关系,(S代表学号,C代表课程,#代表是Primary Key)
S(S#,SNAME,AGE,SEX)
SC(S#,C#,GRADE)
C(C#,CNAME,TEACHER)
求SQL语句;
1,检索选修Maths课的学生,学号和姓名
2,检索至少选修两门课程的学生的学号

[huailairen]

1.
select s.s#,s.sname
from s,sc,c
where s.s#=sc.s# and c.c#=sc.c# and c.cname='Maths'

[huailairen]

2
select s.s#
from s,sc,c
where s.s#=sc.s# and c.c#=sc.c#
group by s.s#
having count(*)>1

[quanyi]

1.
select s.s#,s.sname
from s,sc,c
where s.s#=sc.s# and c.c#=sc.c# and c.cname='Maths'

2
select s.s#
from s,sc,c
where s.s#=sc.s# and c.c#=sc.c#
group by s.s#
having count(*)>1