MySQL查询语句的45道练习

 

 

 

 

 

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

#建学生信息表student
create table student
(
sno varchar(20) not null primary key,
sname varchar(20) not null,
ssex varchar(20) not null,
sbirthday datetime,
class varchar(20)

);
#建立教师表
create table teacher
(
tno varchar(20) not null primary key,
tname varchar(20) not null,
tsex varchar(20) not null,
tbirthday datetime,
prof varchar(20),
depart varchar(20) not null

);
#建立课程表course
create table course
(
cno varchar(20) not null primary key,
cname varchar(20) not null,
tno varchar(20) not null,
foreign key(tno) references teacher(tno)

);
#建立成绩表
create table score
(
sno varchar(20) not null primary key,
foreign key(sno) references student(sno),
cno varchar(20) not null,
foreign key(cno) references course(cno),
degree decimal

);

#添加学生信息
insert into student values('108','曾华','男','1977-09-01','95033');
insert into student values('105','匡明','男','1975-10-02','95031');
insert into student values('107','王丽','女','1976-01-23','95033');
insert into student values('101','李军','男','1976-02-20','95033');
insert into student values('109','王芳','女','1975-02-10','95031');
insert into student values('103','陆君','男','1974-06-03','95031');

#添加教师表
insert into teacher values('804','李诚','男','1958-12-02','副教授','计算机系');
insert into teacher values('856','张旭','男','1969-03-12','讲师','电子工程系');
insert into teacher values('825','王萍','女','1972-05-05','助教','计算机系');
insert into teacher values('831','刘冰','女','1977-08-14','助教','电子工程系');

#添加课程表
insert into course values('3-105','计算机导论','825');
insert into course values('3-245','操作系统','804');
insert into course values('6-166','数字电路','856');
insert into course values('9-888','高等数学','831');
#添加成绩表

insert into score values('103','3-245','86');
insert into score values('105','3-245','75');
insert into score values('109','3-245','68');
insert into score values('103','3-105','92');
insert into score values('105','3-105','88');
insert into score values('109','3-105','76');
insert into score values('103','3-105','64');
insert into score values('105','3-105','91');
insert into score values('109','3-105','78');
insert into score values('103','6-166','85');
insert into score values('105','6-166','79');
insert into score values('109','6-166','81');

1、 查询Student表中的所有记录的Sname、Ssex和Class列。

1	select Sname,Ssex,Class from student

2、 查询教师所有的单位即不重复的Depart列。

1	select distinct Depart from teacher

3、 查询Student表的所有记录。

1	select *  from student

4、 查询Score表中成绩在60到80之间的所有记录。

1	select *  from Score where Degree between 60 and 80

5、 查询Score表中成绩为85，86或88的记录。

1	select *  from Score where Degree in(85,86,88)

6、 查询Student表中“95031”班或性别为“女”的同学记录。

1	select *  from Student where class='95031' or Ssex='女'

7、 以Class降序查询Student表的所有记录。

1	select *  from student order by class desc

8、 以Cno升序、Degree降序查询Score表的所有记录。

1	select *  from Score order by cno asc,degree desc

9、 查询“95031”班的学生人数。

1	select count(*)  from student where class='95031'

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）

1	select Sno,Cno  from Score where Degree=(select max(Degree) from Score)

1	select Sno,Cno  from Score order by  Degree desc limit 0,1

11、     查询每门课的平均成绩。

1	select Cno,avg(degree) from Score group by Cno

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。

1	select avg(Degree) from score where Cno like '3%' and Cno in (select Cno from score group by Cno having count(*)>=5) 用in 不用= 是因为可能会有多个

1	简单写法：select avg(Degree) from score where Cno like '3%' and group by Cno having count(*)>=5

13、     查询分数大于70，小于90的Sno列。

1	select Sno from Score where degree>70 and degree<90

14、     查询所有学生的Sname、Cno和Degree列。

1	select  Sname, Cno,Degree from Score , student where Score.Sno=student.Sno

15、     查询所有学生的Sno、Cname和Degree列。

1	select  Sno,Cname,Degree from Score , Course where Score.Cno=Course.Cno

16、     查询所有学生的Sname、Cname和Degree列。

1	select Sname,Cname,Degree from student,course,score where student.Sno=score.Sno and course.Cno=score.Cno

1	join .. on 写法：select Sname,Cname,Degree from student join score on student.Sno=score.Sno join course on course.Cno=score.Cno

17、     查询“95033”班学生的平均分。

1	select avg(degree) as 'class=95033' from Score where Sno in (select Sno from  Student where Class='95033' )

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。

1	select Sno,Cno,rank from Score,grade where degree between low and upp

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。

1	<span style="color: #000000; font-size: 15px">109同学，选修是3-105课的</span>

1	select * from score where Cno='3-105' and degree>(select max(degree ) from Score where Sno='109' and Cno='3-105' )

1	<span style="font-size: 15px">109同学，没有选修3-105课</span>

1	select * from score where Cno='3-105' and degree>(select max(degree ) from Score where Sno='109')

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

1	选了多门课程并且是这个课程下不是最高分的

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

1	Select * from score where degree>(select degree from Score where Sno='109' and Cno='3-105' )

22、查询和学号为108、101的同学同年出生的所有学生的Sno、Sname和Sbirthday列。

1	select sno,sname,sbirthday  from student where year(sbirthday) = (select year(sbirthday) from student where  sno='108')

1	select sno,sname,sbirthday  from student where year(sbirthday) = (select year(sbirthday) from student where  sno='101')

23、查询“张旭“教师任课的学生成绩。

1	select Sno,degree from score,Course  where score.Cno=Course.Cno and Course.Tno= (select Tno from Teacher where Tname='张旭' )

1	select degree 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。

1	select Tname from Teacher,  Course where Teacher.Tno=Course.Tno and Course.Cno =(select Cno from Score group by Cno having count(*)>5)

1	select Tname from Teacher where tno=( select Tno from Course where cno=( 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。

1	select * from  student where  class in ('95033','95031')

26、  查询存在有85分以上成绩的课程Cno.

1	select Cno from score where degree>85

27、查询出“计算机系“教师所教课程的成绩表。

1	select * from course  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。

1	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')<br>union <br>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')

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。

any:代表括号中任意一个成绩就可以

1	select Cno,Sno,Degree 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.

all:代表括号中的所有成绩

1	select Cno,Sno,Degree from score where cno='3-105' and degree >all(select degree from score where cno='3-245' ) order by degree desc

31、 查询所有教师和同学的name、sex和birthday.

1	select tname,tsex,tbirthday from Teacher union select sname,ssex,sbirthday from Student

32、查询所有“女”教师和“女”同学的name、sex和birthday.

1	select Tname,Tsex,Tbirthday from Teacher where Tsex='女' union select Sname,Ssex,Sbirthday from Student where Ssex='女'

33、 查询成绩比该课程平均成绩低的同学的成绩表。

1	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.

1	select Tname,Depart from Teacher where tno in (select tno from course )

35 、 查询所有未讲课的教师的Tname和Depart.

1	select Tname,Depart from Teacher where Tno not in (select Tno from Course where cno in (select cno from score  ))

36、查询至少有2名男生的班号。

1	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。

1	select * from Student where Sname not  like '王%%'

38、查询Student表中每个学生的姓名和年龄。

1	select Sname, year(now())-year(sbirthday)  from Student

39、查询Student表中最大和最小的Sbirthday日期值。

1	select Max(Sbirthday ),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。

1	select * from Student  order by  class desc, Sbirthday

41、查询“男”教师及其所上的课程。

1	select Tname,Cname from course,teacher where course.tno= teacher.tno and teacher.Tsex='男'

42、查询最高分同学的Sno、Cno和Degree列。

1	select Sno,Cno,Degree from score where degree=(select max(degree) from score)

排序写法：

1	select Sno,Cno,Degree from score order by degree desc limit 0,1

43、查询和“李军”同性别的所有同学的Sname.

1	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.

1	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。

1	select  Sno,Cno,degree from score where Cno=( select Cno from course where Cname='计算机导论') and Sno in (select Sno from student where Ssex='男')

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