2,、列出同時選修了'數(shù)學(xué)’和'數(shù)據(jù)庫’的學(xué)生學(xué)號,、姓名,；

select student.sno,sname

from student,sc

where cno in (select cno from course

where cname='數(shù)學(xué)')and sc.sno=student.sno

intersect

select student.sno,sname

from student,sc

where cno in (select cno from course

where cname='數(shù)據(jù)庫')and sc.sno=student.sno

3、查詢?nèi)鄙俪煽兊乃袑W(xué)生的詳細情況,；

select * from student,sc where Grade is null and student.sno=sc.sno

     查詢?nèi)鄙俪煽兊乃袑W(xué)生的學(xué)號姓名,；

select student.sno sname from student,sc where Grade is null and student.sno=sc.sno

4、查詢與'李勇’ 年齡相同的所有學(xué)生的信息,；

select * from student

where sage =(select sage from student where sname='李勇') and sname <> '李勇’

      查詢與'楊磊’年齡不相同的所有學(xué)生的信息,；

select * from student

where sage <>(select sage from student where sname='楊磊') 

7、按照“學(xué)號,，姓名,，所在院系，不及格課程門數(shù)”的順序列出學(xué)生有課程不及格的情況,。

select student.sno,sname,sdept,count(grade) 不及格門數(shù) from student,sc

where  student.sno=sc.sno and grade<60 group by student.sno,sname,sdept

9,、查詢只被一名學(xué)生選修的課程的課程號；

select cno from sc group by Cno having COUNT(sno)=1