查询语句的练习
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 |
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。
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')
