MYSQL 45道练习题

Posted 2020-10-08

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	grade
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

-- 查询Student表中的所有记录的Sname、Ssex和Class列。
SELECT Sname,Ssex,Class from student

-- 查询教师所有的单位即不重复的Depart列。
SELECT distinct Depart from teacher

-- 查询Student表的所有记录。
SELECT * from student

-- 查询Score表中成绩在60到80之间的所有记录。
SELECT * from Score where grade>60 and grade<80

-- 查询Score表中成绩为85，86或88的记录。
SELECT * from Score where grade in (85,86,88)

-- 查询Student表中“95031”班或性别为“女”的同学记录。
SELECT * from Student where class="95031" or Ssex=false

-- 以Class降序查询Student表的所有记录。
SELECT * from Student order by Class desc

-- 以Cno升序、Degree降序查询Score表的所有记录。
SELECT * from score order by Cno asc,grade desc

-- 查询“95031”班的学生人数。
SELECT count(*) from student where Class = ‘95031‘

-- 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）
SELECT * from score order by grade desc

-- 查询每门课的平均成绩。
SELECT Cno, avg(grade) from score group by Cno

-- 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。
SELECT Cno , avg(grade) from score where Cno like ‘3%‘ group by Cno having count(Sno)>=5

SELECT avg(grade) from score where Cno in(
SELECT Cno from score where Cno like ‘3%‘
and
Cno in(
SELECT Cno from score group by Cno having count(Sno)>=5
)
)
group by Cno
-- 查询分数大于70，小于90的Sno列。
SELECT Sno from score where grade>70 and grade<90

-- 查询所有学生的sname、cno和degree列
SELECT Sname,Cno,grade from score join student on score.Sno=student.Sno

-- 查询所有学生的sno、sname和degree列
SELECT Sno,Cname,grade from score join course on score.Cno=course.Cno

-- 查询所有学生的sname、cname和degree列

SELECT Sname,Cname,grade from score join student on score.Sno=student.Sno
join course on score.Cno=course.Cno

SELECT Sname,Cname,grade from student,course,score where score.Cno=course.Cno and
score.Sno=student.Sno

-- 查询“95033”班学生的平均分

SELECT avg(grade) from score join student on score.Sno=student.Sno where class="95033"
--
-- 使用下面命令建立一个grade表
create table grad (
low int (3),
upp int (3),
rank char (1)
)
insert into grad values (90,100,‘A‘)
insert into grad values (80,89,‘B‘)
insert into grad values (70,79,‘C‘)
insert into grad values (60,69,‘D‘)
insert into grad values (0,59,‘E‘)

-- 查询所有同学的sno、cno和rank列
SELECT Sno,Cno,rank from score,grad where grade between low and upp

-- 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 grade from score where Cno=‘3-105‘ and grade>(
SELECT grade from score where Sno=109 and Cno=‘3-105‘
)

-- 查询score中选修多门课程的同学中分数为非最高分成绩的记录
SELECT sum(grade) from score group by Sno having count(Sno)>=2
order by sum(grade) desc

SELECT sum(grade) from score where Sno in(
SELECT Sno from score group by Sno having count(Sno)>=2
)
group by Sno-- 分组求和，否则求出总数

-- 查询成绩高于学号为109、课号为3-105 的成绩的所有记录
SELECT * from score where grade>(
SELECT grade from score where Sno=109 and Cno=‘3-105‘
)

-- 查询京津教师任课的学生成绩
SELECT grade from score where Cno in(
SELECT Cno from course where Tno in(
SELECT Tno from teacher where Tname=‘京津‘
)
)

SELECT grade from score join course on score.Cno=course.Cno
join teacher on course.Tno=teacher.Tno where Tname=‘京津‘

--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(Sno)>=5
)
)
-- group by Cno

-- 查询95033班和95031班全体学生的记录
SELECT * from score where Sno in(
SELECT Sno from student where class in(95033,95031)
)

-- 查询存在有85分以上成绩的课程Cno

SELECT distinct Cname from course join score on course.Cno=score.Cno
where grade>=85

SELECT distinct Cno from score where grade>=85

-- 查询出 计算机系 教师所教课程的成绩表
SELECT grade from score where Cno in(
SELECT Cno from course where Tno in(
SELECT Tno from teacher where Depart=‘计算机系‘
)
)

SELECT grade from score join course on score.Cno=course.Cno
join teacher on course.Tno=teacher.Tno
where Depart=‘计算机系‘

-- 查询计算机系与电子工程系不同职称的Tname和Prof教师的
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 all
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 a where Prof
not in (SELECT Prof from teacher b where a.Depart != b.Depart)
-- 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 grade >
any(SELECT grade from score where Cno=‘3-245‘
)
order by grade asc
-- all 所有，any 任意
-- 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 grade >
(SELECT max(grade) from score where Cno=‘3-245‘
)

 

-- 查询所有教师和同学的name、sex和birthday.
SELECT Tname,sex from teacher
union all
SELECT Sname,Ssex from student

-- 查询所有“女”教师和“女”同学的name、sex和birthday.
SELECT Tname,sex from teacher where sex=0
union all
SELECT Sname,Ssex from student where Ssex=0

-- 查询成绩比该课程平均成绩低的同学的成绩表。

SELECT * from score where Cno=‘3-245‘ and grade<
(SELECT avg(grade) from score where Cno=‘3-245‘
)
union
SELECT * from score where Cno=‘3-105‘ and grade<
(SELECT avg(grade) from score where Cno=‘3-105‘
)
union
SELECT * from score where Cno=‘6-116‘ and grade<
(SELECT avg(grade) from score where Cno=‘6-116‘
)

SELECT * from score join (SELECT Cno,avg(grade) as a from score group by Cno) as b on
(b.Cno=score.Cno) where grade<a

Select * from score a where grade<(select avg(grade) from score b where a.cno=b.cno)
-- 查询所有任课教师的Tname和Depart.
SELECT Tname,Depart from teacher where Tno in(
SELECT Tno from course where Cno in(
SELECT Cno from score group by Cno
)
)

--查询所有未讲课的教师的Tname和Depart.

SELECT Tname,Depart from teacher where Tno not in(
SELECT Tno from course where Cno in(
SELECT Cno from score group by Cno
)
)

SELECT Tname,Depart from teacher where Tno not in(
SELECT Tno from course where Cno in(
SELECT distinct Cno from score
)
)

-- 查询至少有2名男生的班号。

SELECT distinct class from student where Ssex in(
SELECT Ssex from student where Ssex=1 and Ssex in(
SELECT Ssex from student group by Ssex having count(Ssex)>=2
)
)
SELECT class from student where Ssex=‘1‘ group by class having count(*)>=2

-- 查询Student表中不姓“王”的同学记录。

SELECT * from student where Sname not like ‘王%‘

-- 查询Student表中每个学生的姓名和年龄。

SELECT Sno,Sname from student

alter table student add column birthday varchar(30);
select sname as ‘姓名‘,(year ( date ( now() )) - year(birthday) ) as ‘年龄‘ from student;
select sname,(year(date(now()) ) -year(birthday) ) from student;
-- 查询Student表中最大和最小的Sbirthday日期值。
SELECT max(Sno)from student
union
SELECT min(Sno)from student

SELECT max(Sno) as ‘最大值‘,min(Sno) ‘最小值‘ from student
--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,Sno desc

-- 查询“男”教师及其所上的课程。

SELECT Cname from course where Tno in(
SELECT Tno from teacher where sex=1
)

-- 查询最高分同学的Sno、Cno和Degree列。

SELECT Sno,Cno,grade from score where grade in(
SELECT max(grade) from score
)

--查询和“李军”同性别的所有同学的Sname.

SELECT Sname from student where Ssex in (
SELECT Ssex from student where Sname=‘张三‘
)

--查询和“李军”同性别并同班的同学Sname.

SELECT Sname from student where class in (
SELECT class from student where Sname=‘张三‘
)
and
Ssex in(
SELECT Ssex from student where Sname=‘张三‘
)

--查询所有选修“计算机导论”课程的“男”同学的成绩表。
SELECT grade from score where Cno in(
SELECT Cno from course where Cname=‘计算机导论‘
)
and
Sno in(
SELECT Sno from student where
Ssex in(
SELECT Ssex from student where Ssex=1
)
)