MySQL语言 数据库练习题分解。

一、            设有一数据库，包括四个表：学生表（Student）、课程表（Course）、成绩表（Score）以及教师信息表（Teacher）。四个表的结构分别如表1-1的表（一）~表（四）所示，数据如表1-2的表（一）~表（四）所示。用SQL语句创建四个表并完成相关题目。

表1-1数据库的表结构 

表（一）Student (学生表)

属性名	数据类型	可否为空	含 义
Sno	varchar (20)	否	学号（主码）
Sname	varchar (20)	否	学生姓名
Ssex	varchar (20)	否	学生性别
Sbirthday	datetime	可	学生出生年月
Class	varchar (20)	可	学生所在班级

表（二）Course（课程表）

属性名	数据类型	可否为空	含 义
Cno	varchar (20)	否	课程号（主码）
Cname	varchar (20)	否	课程名称
Tno	varchar (20)	否	教工编号（外码）

表（三）Score(成绩表)

属性名	数据类型	可否为空	含 义
Sno	varchar (20)	否	学号（外码）
Cno	varchar (20)	否	课程号（外码）
Degree	Decimal(4,1)	可	成绩
主码：Sno+ Cno

表（四）Teacher(教师表)

属性名	数据类型	可否为空	含 义
Tno	varchar (20)	否	教工编号（主码）
Tname	varchar (20)	否	教工姓名
Tsex	varchar (20)	否	教工性别
Tbirthday	datetime	可	教工出生年月
Prof	varchar (20)	可	职称
Depart	varchar (20)	否	教工所在部门

表1-2数据库中的数据

表（一）Student

Sno	Sname	Ssex	Sbirthday	class
108	曾华	男	1977-09-01	95033
105	匡明	男	1975-10-02	95031
107	王丽	女	1976-01-23	95033
101	李军	男	1976-02-20	95033
109	王芳	女	1975-02-10	95031
103	陆君	男	1974-06-03	95031

表（二）Course

Cno	Cname	Tno
3-105	计算机导论	825
3-245	操作系统	804
6-166	数字电路	856
9-888	高等数学	831

表（三）Score

Sno	Cno	Degree
103	3-245	86
105	3-245	75
109	3-245	68
103	3-105	92
105	3-105	88
109	3-105	76
101	3-105	64
107	3-105	91
108	3-105	78
101	6-166	85
107	6-166	79
108	6-166	81

表（四）Teacher

Tno	Tname	Tsex	Tbirthday	Prof	Depart
804	李诚	男	1958-12-02	副教授	计算机系
856	张旭	男	1969-03-12	讲师	电子工程系
825	王萍	女	1972-05-05	助教	计算机系
831	刘冰	女	1977-08-14	助教	电子工程系

1、 查询Student表中的所有记录的Sname、Ssex和Class列。     #读取指定列

2、 查询教师所有的单位即不重复的Depart列。      #去重查询

3、 查询Student表的所有记录。   #简单读取

4、 查询Score表中成绩在60到80之间的所有记录。 #范围查询

5、 查询Score表中成绩为85，86或88的记录。 #离散查询

6、 查询Student表中“95031”班或性别为“女”的同学记录。#多条件查询

7、 以Class降序查询Student表的所有记录。   #排序查询

8、 以Cno升序、Degree降序查询Score表的所有记录。              #排序查询

9、 查询“95031”班的学生人数。                       #集合函数，取所有的数据条数

10、 查询Score表中的最高分的学生学号和课程号。（子查询或者排序）  #排序查询

11、 查询每门课的平均成绩。 #分组查询，用简单分组查询将count换avg(平均值的列明)

12、查询Score表中至少有5名学生选修的并以3开头的课程的平均分数。

理解一：
select avg(degree) from score where cno like'3%' and cno in(select cno from score group by cno having count(*)>4)
理解二：
select avg(degree) from score group by cno having count(*)>4 and cno like '3%'

13、查询分数大于70，小于90的Sno列。 #范围查询讲*改为Sno就行

14、查询所有学生的Sname、Cno和Degree列。 #笛卡尔积

select sname,cno,degree from score,student where student.sno=score.sno

15、查询所有学生的Sno、Cname和Degree列。#笛卡尔积

select sno,cname,degree from course,score where course.Cno=score.Cno

16、查询所有学生的Sname、Cname和Degree列。#笛卡尔积    and是与的关系

select sname,cname,degree from student,course,score where student.Sno=score.Sno and course.cno=score.Cno 

17、 查询“95033”班学生的平均分。

select avg(degree) from score where degree in(select degree from score where sno in(select sno from student where class=''))  

用Avg先求出那个列的所有平均值，in里面有链接要把 那个表 里要求的平均值的列拿出来，在拿出本表里的主键，in与外部再链接，sno是另一个和求平均分有直属关系的表里的主键。然后和他有直属关系表里的class列=’95033’  就只求出95033班的学生平均分了。

18、 假设使用如下命令建立了一个grade表：

create table grade(low  int(3),upp  int(3),rank  char(1))

insert into grade values(90,100,’A’)

insert into grade values(80,89,’B’)

insert into grade values(70,79,’C’)

insert into grade values(60,69,’D’)

insert into grade values(0,59,’E’)

现查询所有同学的Sno、Cno和rank列。

19、  查询选修“3-105”课程的成绩高于“109”号同学成绩的所有同学的记录。

select * from Score where Cno ='3-105' and Degree>(select Degree from Score where Sno = '' and Cno = '3-105')

20、查询score中选学多门课程的同学中分数为非最高分成绩的记录。

 理解1

select * from Score a where Sno in (select Sno from Score group by Sno having count(*)>1 ) and Degree not in (select max(Degree) from Score b where b.Cno = a.Cno)

理解2

select * from Score a where Sno in (select Sno from Score group by Sno having count(*)>1 )  and Degree not in (select max(Degree) from Score a where Sno in (select Sno from Score group by Sno having count(*)>1 ))

21、 查询成绩高于学号为“109”、课程号为“3-105”的成绩的所有记录。

select * from Score where Degree >(select Degree from Score where Sno = '' and Cno = '3-105')

 

22、查询和学号为108的同学同年出生的所有学生的Sno、Sname和Sbirthday列。

select Sno,Sname,Sbirthday from Student where YEAR(Sbirthday) = (select YEAR(Sbirthday) from Student where Sno = '')

23、查询“张旭“教师任课的学生成绩。

select * from Score where Cno in(select Cno from Course where Tno =(select Tno from Teacher where Tname='张旭'))

24、查询选修某课程的同学人数多于5人的教师姓名。

select Tname from Teacher where Tno in(select Tno from Course where Cno in(select Cno from Score group by Cno having count(*) > 5))

25、查询95033班和95031班全体学生的记录。

select * from Student where Class in('','')

26、  查询存在有85分以上成绩的课程Cno

select distinct Cno from Score where Degree > 85

27、查询出“计算机系“教师所教课程的成绩表。

select * from Score where Cno in(select Cno from Course where Tno in(select Tno from Teacher where depart = '计算机系'))

28、查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。

select Tname,prof from Teacher where prof not in(select prof from Teacher where depart = '计算机系' and prof in(select prof from Teacher where depart='电子工程系' ))

29、查询选修编号为“3-105“课程且成绩至少高于选修编号为“3-245”的同学的Cno、Sno和Degree,并按Degree从高到低次序排序。

select * from Score where Cno='3-105' and Degree>any(select Degree from Score where Cno ='3-245') order by Degree desc

30、查询选修编号为“3-105”且成绩高于选修编号为“3-245”课程的同学的Cno、Sno和Degree.

select * from Score where Cno='3-105' and Degree>all(select Degree from Score where Cno ='3-245')

31、 查询所有教师和同学的name、sex和birthday.

select Sname,Ssex,Sbirthday from Student 

union

select Tname,Tsex,Tbirthday from Teacher

32、查询所有“女”教师和“女”同学的name、sex和birthday.

select Sname,Ssex,Sbirthday from Student where Ssex='女' 

union

select Tname,Tsex,Tbirthday from Teacher where Tsex='女'

33、 查询成绩比该课程平均成绩低的同学的成绩表。

select * from Score a where Degree<(select avg(Degree) from Score b where b.Cno = a.Cno)

34、 查询所有任课教师的Tname和Depart.

select Tname,depart from Teacher where Tno in (select Tno from Course )

成绩表上：select Tname,depart from Teacher where Tno in(select Tno from Course where Cno in(select Cno from Score))

35 、 查询所有未讲课的教师的Tname和Depart.

select Tname,depart from Teacher where Tno in(select Tno from Course where Cno not in(select Cno from Score))

36、查询至少有2名男生的班号。

select Class from Student where Ssex='男' group by Class having count(*)>1

37、查询Student表中不姓“王”的同学记录。

select * from Student where Sno not in(select Sno from Student where Sname like '王%')

38、查询Student表中每个学生的姓名和年龄。

select Sname,YEAR(now())-YEAR(Sbirthday) from Student

39、查询Student表中最大和最小的Sbirthday日期值。

select max(Sbirthday) from Student union select min(Sbirthday) from Student

40、以班号和年龄从大到小的顺序查询Student表中的全部记录。

select * from Student order by Class desc,Sbirthday

41、查询“男”教师及其所上的课程。

select * from Teacher join Course on Teacher.Tno = Course.Tno where Teacher.Tsex='男'

42、查询最高分同学的Sno、Cno和Degree列。

select * from Score where Degree = (select max(Degree) from Score )

43、查询和“李军”同性别的所有同学的Sname.

select Sname from Student where Ssex = (select Ssex from Student where Sname='李军')

44、查询和“李军”同性别并同班的同学Sname.

select Sname from Student where Ssex = (select Ssex from Student where Sname='李军') and Class=(select Class from Student where Sname = '李军')

45、查询所有选修“计算机导论”课程的“男”同学的成绩表。

 select * from Score where Sno in(select Sno from Student where Ssex='男') and Cno in(select Cno from Course where Cname='计算机导论')

老师讲解的一些代码：：：

1.select sname,ssex,class from student
2.select distinct depart from teacher
3.select * from student
4.select * from score where degree btween 60 and 80;
5.select * from score where degree in(85,86,88)
6.select * from student where class='' or ssex='女'
7.select * from student order by class desc
8.select * from score order by cno,degree desc
9.select count(*) from student where class=''
10.select sno,cno from score where degree=(select max(degree) from score)
select * from score order by degree desc limit 0,1
11.select cno,avg(degree) from score group by cno

12.select avg(degree) from score where cno like'3%' and cno in(select cno from score group by cno having count(*)>4)

select avg(degree) from score group by cno having count(*)>4 and cno like '3%'

13.select sno from score where degree>70 and degree<90

14.select student.sname,score.cno,score.degree from student,score where student.sno = score.sno

15.select score.sno,course.cname,score.degree from score,course where score.cno=course.cno

16.select student.sname,course.cname,degree from score,student,course where student.sno=score.sno and score.cno=course.cno

17.select avg(degree) from score where sno in(select sno from student where class='')

18.select sno,cno,rank from score,grade where degree between low and upp

19.(1)select * from score where cno = '3-105' and degree>(select max(degree) from score where sno='')
(2)select * from score where cno = '3-105' and degree>(select max(degree) from score where sno='' and cno='3-105')

20.(1)select * from score where sno in(select sno from score group by sno having count(*)>1) and degree<(select max(degree) from score)

(2)select * from score a where sno in(select sno from score group by sno having count(*)>1) and degree<(select max(degree) from score b where b.cno = a.cno)

21.select * from score where degree>(select degree from score where sno='' and cno='3-105')

22.select sno,sname,sbirthday from student where YEAR(sbirthday) = (select YEAR(sbirthday) from student where sno='')

23.select * from score where cno in(select cno from course where tno =(select tno from teacher where tname='张旭'))

24.select tname from teacher where tno in(select tno from course where cno in(select cno from score group by cno having count(*)>5))

25.select * from student where class in('','')

26.select distinct cno from score where degree>85

27.select * from score where cno in(select cno from course where tno in(select tno from teacher where depart='计算机系'))

28.select tname,prof from teacher where depart='计算机系'  and prof not in(select prof from teacher where depart='电子工程系')
union
select tname,prof from teacher where depart='电子工程系'  and prof not in(select prof from teacher where depart='计算机系')

select tname,prof from teacher where prof not in( select prof from teacher where depart='计算机系'  and prof in(select prof from teacher where depart='电子工程系'))

29.select * from score where cno='3-105' and degree>any(select degree from score where cno='3-245')

30.select * from score where cno='3-105' and degree>all(select degree from score where cno='3-245')

31.select sname,ssex,sbirthday from student
union
select tname,tsex,tbirthday from teacher

32.select sname,ssex,sbirthday from student where ssex='女'
union
select tname,tsex,tbirthday from teacher where tsex='女'

33.select * from score a where degree<(select avg(degree) from score b where b.cno =a.cno )

34.select tname,depart from teacher where tno in(select tno from course where cno in(select cno from score))

35.select tname,depart from teacher where tno in(select tno from course where cno not in(select cno from score))

36.select class from student where ssex='男' group by class having count(*)>1 

37.select  * from student where sname not like '王%'

38.select sname,year(now())-year(sbirthday) from student

39.select max(sbirthday),min(sbirthday) from student

40.select * from student order by class desc,sbirthday

41.select tname,cname from teacher,course where teacher.tno = course.tno and tsex='男'

42.select * from score where degree=(select max(degree) from score)

43.select sname from student where ssex=(select ssex from student where sname='李军')

44.select sname from student where ssex=(select ssex from student where sname='李军') and class=(select class from student where sname='李军')

45.select * from score where sno in(select sno from student where ssex='男') and cno in(select cno from course where cname='计算机导论')