MySQL查询语句的45道练习
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
|
|
|
1
|
select
*
from
score
where
Cno=
'3-105'
and
degree>(
select
max
(degree )
from
Score
where
Sno=
'109'
and
Cno=
'3-105'
)
|
|
1
|
|
|
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'
)
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'
)
|
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'
)
|