• 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。

                     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)

    学号(主码)

    Sname

    varchar (20)

    学生姓名

    Ssex

    varchar (20)

    学生性别

    Sbirthday

    datetime

    学生出生年月

    Class

    varchar (20)

    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)

    课程号(主码)

    Cname

    varchar (20)

    课程名称

    Tno

    varchar (20)

    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)

    学号(外码)

    Cno

    varchar (20)

    课程号(外码)

    Degree

    Decimal(4,1)

    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)

    教工编号(主码)

    Tname

    varchar (20)

    教工姓名

    Tsex

    varchar (20)

    教工性别

    Tbirthday

    datetime

    教工出生年月

    Prof

    varchar (20)

    职称

    Depart

    varchar (20)

    教工所在部门

    1-2数据库中的数据

    表(一)Student

    Sno

    Sname

    Ssex

    Sbirthday

    class

    108

    曾华

    1977-09-01

    95033

    105

    匡明

    1975-10-02

    95031

    107

    王丽

    1976-01-23

    95033

    101

    李军

    1976-02-20

    95033

    109

    王芳

    1975-02-10

    95031

    103

    陆君

    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

    1958-12-02

    副教授

    计算机系

    856

    张旭

    1969-03-12

    讲师

    电子工程系

    825

    王萍

    1972-05-05

    助教

    计算机系

    831

    刘冰

    1977-08-14

    助教

    电子工程系

     

    复制代码
    复制代码
    #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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  • 原文地址:https://www.cnblogs.com/aqxss/p/6563625.html
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