数据库练习题

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。

SELECT * FROM `student`

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

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` 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:              #子查询更准确,先查询出最高分,再查询学号和课程号

SELECT sno, cno FROM `score` WHERE degree = ( SELECT MAX( degree ) FROM score )           

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())

分组:按cno分组

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 (                             #in表示范围

SELECT cno
FROM score
WHERE cno LIKE '3%'             #筛选出以3开头的课程
GROUP BY cno
HAVING COUNT( * ) >=5           #整个表用where筛选,分完组后用having进行筛选       #having只能跟在group by 之后

)
GROUP BY cno

-查询以3开头的课程信息

SELECT * FROM `score` WHERE cno LIKE '3%'

-查询选修人数>=5的课程编号

SELECT cno FROM `score` GROUP BY cno HAVING COUNT( * ) >=5

13、查询分数大于70，小于90的Sno列。

SELECT sno FROM `score` WHERE degree> 70 AND degree< 90                  # between是>=70,<=90

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      #笛卡儿积   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` JOIN course ON course.cno = score.cno

16、查询所有学生的Sname、Cname和Degree列。

SELECT sname, cname, degree FROM score LEFT JOIN course ON score.cno = course.cno LEFT JOIN student ON score.sno = student.sno

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 ) , class FROM `score` JOIN student ON score.sno = student.sno WHERE student.class =95033 GROUP BY class  

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 grade JOIN score 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 cno = '3-105' AND sno =109 ) 

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 * 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 tname 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 ( ‘95031’, ‘95033’ ) 

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'))

方法2.

SELECT * 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') ORDER BY degree DESC 

31、 查询所有教师和同学的name、sex和birthday.

SELECT sname AS name, ssex AS sex, sbirthday AS birthday 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 AS name, ssex AS sex, sbirthday AS birthday 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 cno FROM `score` GROUP BY cno))

方法2.

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( * ) >=2

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 ) AS age 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 * 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。

方法1:
SELECT * FROM score WHERE degree = (SELECT MAX( degree ) FROM score )

方法2:
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 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.

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 * 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')