数据库练习
from：http://www.cnblogs.com/yy01/p/5421157.html
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 |
Char(3) |
否 |
学号（主码） |
|
Sname |
Char(8) |
否 |
学生姓名 |
|
Ssex |
Char(2) |
否 |
学生性别 |
|
Sbirthday |
datetime |
可 |
学生出生年月 |
|
Class |
Char(5) |
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 |
Char(5) |
否 |
课程号（主码） |
|
Cname |
Varchar(10) |
否 |
课程名称 |
|
Tno |
Char(3) |
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 |
Char(3) |
否 |
学号（外码） |
|
Cno |
Char(5) |
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 |
Char(3) |
否 |
教工编号（主码） |
|
Tname |
Char(4) |
否 |
教工姓名 |
|
Tsex |
Char(2) |
否 |
教工性别 |
|
Tbirthday |
datetime |
可 |
教工出生年月 |
|
Prof |
Char(6) |
可 |
职称 |
|
Depart |
Varchar(10) |
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。
select Sname,Ssex,Class from Student
2、 查询教师所有的单位即不重复的Depart列。
select distinct Depart from Teacher
3、 查询Student表的所有记录。
4、 查询Score表中成绩在60到80之间的所有记录并按成绩顺序排列。
select * from Score where Degree >=60 and Degree <=80 order by Degree
select * from Score where Degree between 60 and 80 order by Degree
5、 查询Score表中成绩为85，86或88的记录。
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。
select * from Student where Class =95031 or Ssex ='女'
7、 以Class降序查询Student表的所有记录。
select * from Student order by Class desc
8、 以Cno升序、Degree降序查询Score表的所有记录。
select * from Score order by Cno,Degree desc
9、 查询“95031”班的学生人数。
select Count from Student 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）
子查询:
select Sno,Cno from Score where(Degree =(select max (Degree) from score))//子查询更准确,先查询出最高分,再查询学号和课程号
排序:
select Cno,Sno from Score order by Degree desc limit 0,1
11、 查询每门课的平均成绩。按照课程分组(group by),然后求每门课平均分(avg())
select avg(Degree),Cno 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。
select avg(Degree),Cno from Score where Cno in(select Cno from Score where Cno like '3%' group by Cno having count(*)>=5 ) group by Cno limit 0,30
select * from Score where Cno like '3%' limit 0,30 //查询以3开头的课程信息
select Cno from Score group by Cno having count ( * ) >=5 limit 0,30 //查询选修人数>=5的课程编号
13、查询分数大于70，小于90的Sno列。
select Sno from Score where Degree >70 and Degree <90 limit 0,30
14、查询所有学生的Sname、Cno和Degree列。
方法1.
select (select Sname from Student where Student.Sno = Score.Sno) , Cno,Degree from Score
方法2.
select Sname,Cno,Degree from Score,Student where Score.Sno = Student.Sno //穷举,,非常浪费资源,不建议使用
方法3.
select Sname,Cno,Degree from Score join Student on Score.Sno = Student.Sno
15、查询所有学生的Sno、Cname和Degree列。
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。
select Sname,Cname,Degree from Score,Course,Student where Score.Cno = Course.Cno and Score.Sno = Student.Sno
17、 查询“95033”班学生的平均分。
select avg(Degree) 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。
select Sno,Cno,rank from Score join grade on 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。
select * from Score where Cno = '3-105' and Degree >(select degree from Score where Sno = '109' and Cno = '3-105')
20、查询score中选学多门课程的同学中分数为非最高分成绩的记录。
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。
select * from Score where Degree>(select Degree from Score where Sno='109' and Cno = '3-105')
22、查询和学号为108的同学同年出生的所有学生的Sno、Sname和Sbirthday列。
select Sno,Sname,Sbirthday from Student where YEAR(Sbirthday) =( select YEAR(Sbirthday) from Student where Sno = '108')
23、查询“张旭“教师任课的学生成绩。
select * 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。
select * from Teacher where Tno in( select Tno from Course where Cno in( 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。
select * from Student where class in('95033','95031')
26、 查询存在有85分以上成绩的课程Cno.
select distinct Cno from Score where Degree>85
27、查询出“计算机系“教师所教课程的成绩表。
select * from Score 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。
select * from Teacher where prof not in(select prof from Teacher where Depart ='计算机系' and prof in (select prof from Teacher where Depart = '电子工程系'))
elect * from Teacher where prof in(select 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 * from Teacher where prof in(select 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。
select * 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.
select * from Score where Cno = '3-105' and Degree>All(select Degree from Score where Cno = '3-245')
31、 查询所有教师和同学的name、sex和birthday.
select Sname,Ssex,Sbirthday from Student union
select Tname,Tsex,Tbirthday from Teacher
32、查询所有“女”教师和“女”同学的name、sex和birthday.
select Sname,Ssex,Sbirthday from Student where Ssex = '女' union
select Tname,Tsex,Tbirthday from Teacher where Tsex = '女'
33、 查询成绩比该课程平均成绩低的同学的成绩表。
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.
select Tname,Depart from Teacher where Tno in( select Tno from Course where Cno in(select distinct Cno from Score))
35 、 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 distinct Cno from Score))
36、查询至少有2名男生的班号。
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。
select * from Student where Sname not like '王%'
38、查询Student表中每个学生的姓名和年龄。
select Sname,YEAR(now())-YEAR(Sbirthday) from Student
39、查询Student表中最大和最小的Sbirthday日期值。
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。
select * from Student order by class desc,Sbirthday
41、查询“男”教师及其所上的课程。
select Cno from Course where Tno in(select Tno from Teacher where Tsex = '男')
42、查询最高分同学的Sno、Cno和Degree列。
select * from Score where Degree = (select max(Degree) from Score)
select * 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.
select * 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.
select * 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 * from Score where Sno in (select Sno from Student where Ssex = '男') and Cno in(select Cno from Course where Cname ='计算机导论')
