MySQL 嵌套查询_嵌套查询和嵌套结果的区别

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自测题：

1、查询哪些课程没有人选修列出课程号和课程名；

[code]select cno,cname

from course

where cno not in(

select distinct cno

from sc)[/code]

2、用子查询实现如下查询：

(1)查询选修了1号课程的学生姓名和所在系；

[code]select sname,sno

from student

where sno in(

select sno

from sc

where cno=1)[/code]

(2)查询“数据库”成绩在80分以上的学生的学号和姓名；

[code]Select sno,sname

From student

Where sno in(

select sno

from course,sc

where course.cno=sc.cno and course.cname=’数据库’ and grade>=80)[/code](3)查询计算机系最高成绩。

[code]select top 1 grade

from student,sc

where student.sno=sc.sno and sdept=’CS’

order by grade desc[/code]

3、查询同时选修了1号和2号课程的学生学号

[code]select sno

from sc

where cno=1 and sno in(

select sno

from sc

where cno=2)[/code]

4、查询选修了“离散数学”的学生姓名(连接查询)

[code]select sname

from student

where sno in(

select sno

from course,sc

where course.cno=sc.cno and course.cname=’离散数学’)[/code]

5、查询选修课程名为“数据库”的学生姓名(子查询)

[code]select sname

from student

where sno in(

select sno

from course,sc

where course.cno=sc.cno and course.cname=’数据库’)[/code]

6、查询与张天和张琪在同一个系的学生

[code]select *

from student

where sdept in(

select sdept

from student

where sname=’张天’ or sname=’张琪’)[/code]

查询与张天或张琪不在同一个系的学生

[code]select *

from student

where sdept not in(

select sdept

from student

where sname=’张天’ or sname=’张琪’)[/code]

7、查询比信息系所有学生年龄大的学生姓名

[code]select sname

from student s1

where s1.sage>all(

select sage

from student s2

where s2.sdept=’CS’)[/code]

8、查询比张天平均成绩高的学生姓名

[code]select sname

from student

where student.sno in(

select sno

from sc

group by sno

having avg(grade) >(

select avg(grade) as avg_grade2

from sc sc2,student

where student.sno=sc2.sno and sname=’刘晨’

group by sc2.sno)

)[/code]9、查询比学号为200215121学生年龄大的学生

[code]select *

from student s1

where s1.sage>(

select sage

from student s2

where s2.sno=’200215121′)[/code]

10、查询各系总分最高的学生学号

[code]Select sdept,student.sno

from student,sc

where student.sno=sc.sno

group by sdept,student.sno

having sum(grade)>=all(

select sum(grade)

from student,sc

where student.sno=sc.sno and sdept=student.sdept

group by student.sno)[/code]

11、查询选修了以6号课程为先行课的所有课程的学生学号。

[code]select distinct sno

from sc

where sc.cno in(

select cno

from course

where cpno=6)[/code]

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