实验5 创建视图(6)

25、求各个课程号及相应的选课人数

select Cno,Count(Sno) from SC group by Cno

26、查询选修了2们以上课程的学生学号

select Sno from SC Group by Sno having count(*)>2

27、查询每个学生及其选修课程的情况

select Student.*,SC.* from student,SC

where Student.Sno=SC.Sno

28、查询每个学生选修课程情况（用自然连接）

select Student.Sno,Sname,Ssex,Sage,Sdept,Cno,Greade from student,SC

where Student.Sno=SC.Sno

29、查询每门课的间接先修课

select x.Cno,y.Cpno from Course x,Course y where x.Cpno=y.Cno

30、查询选修课程2且成绩在85分以上的所有学生

select Student.Sno,Sname from Student,SC

where Student.Sno=SC.Sno and SC.Cno='2'and SC.Greade>85

31、查询每个学生的学号、姓名、选修的课程名级成绩

select Student.Sno,Sname,Cname,Greade from Student,SC,Course where Student.Sno=SC.Sno and SC.Cno=Course.Cno