MySQL3.5练习题~加上前面的分析

可以做下这套题加深印象，并且后面会补充一点前面没写却用的到的知识点~~

数据库结构
创建四张表 分别存储 学生信息 课程信息 分数 讲师信息表 存储相应数据
学生信息表 Student
字段名	字段类型	字段约束 / 含义
Sno	Varchar(3)	Not null  / 学员编号
Sname	Varchar(4)	Not null  / 学员姓名 
Ssex	Varchar(2)	Not null  / 性别
Sbirthday	Datetime	生日
Classnum	Varchar(5)	班级号

CREATE TABLE STUDENT
(
SNO VARCHAR(3) NOT NULL,
SNAME VARCHAR(4) NOT NULL,
SSEX VARCHAR(2) NOT NULL,
SBIRTHDAY DATETIME,
CLASS VARCHAR(5)
)
课程信息表 course
字段名	字段类型	字段约束 / 含义
Cno	Varchar(5)	Not null / 课程编号
Cname	Varchar(10)	Not null / 课程名称
Tno	Varchar(10)	Not null / 授课老师编号


CREATE TABLE COURSE
(CNO VARCHAR(5) NOT NULL,
CNAME VARCHAR(10) NOT NULL,
TNO VARCHAR(10) NOT NULL)
成绩表score
字段名	字段类型	字段约束 / 含义
Sno	Varchar(3)	Not null  / 学员编号
Cno	Varchar(5)	Not null  / 课程编号
Degree	Double(3,1)	Not null  / 分数

CREATE TABLE SCORE
(SNO VARCHAR(3) NOT NULL,
CNO VARCHAR(5) NOT NULL,
DEGREE NUMERIC(10, 1) NOT NULL)
讲师表teacher
字段名	字段类型	字段约束 / 含义
Tno	Varchar(3)	Not null  / 讲师编号
Tname	Varchar(4)	Not null  / 讲师姓名
Tsex	Varchar(2)	Not null  / 讲师性别
Tbirthday	Datetime	Not null  / 出生日期
Prof	Varchar(6)	等级
Depart	Varchar(10)	所属院系

CREATE TABLE TEACHER
(TNO VARCHAR(3) NOT NULL,
TNAME VARCHAR(4) NOT NULL, TSEX VARCHAR(2) NOT NULL,
TBIRTHDAY DATETIME NOT NULL, PROF VARCHAR(6),
DEPART VARCHAR(10) NOT NULL);

向表中存储数据
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (108 ,'曾华' ,'男' ,1977-09-01,95033);
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (105 ,'匡明' ,'男' ,1975-10-02,95031);
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (107 ,'王丽' ,'女' ,1976-01-23,95033);
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (101 ,'李军' ,'男' ,1976-02-20,95033);
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (109 ,'王芳' ,'女' ,1975-02-10,95031);
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (103 ,'陆君' ,'男' ,1974-06-03,95031);
GO
INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('3-105' ,'计算机导论',825)
INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('3-245' ,'操作系统' ,804);
INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('6-166' ,'数据电路' ,856);
INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('9-888' ,'高等数学' ,100);
GO
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (103,'3-245',86);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (103,'3-245',86);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (109,'3-245',68);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (103,'3-105',92);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (105,'3-105',88);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (109,'3-105',76);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (101,'3-105',64);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (107,'3-105',91);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (108,'3-105',78);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (101,'6-166',85);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (107,'6-106',79);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (108,'6-166',81);
GO
INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) 
VALUES (804,'李诚','男','1958-12-02','副教授','计算机系');
INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) 
VALUES (856,'张旭','男','1969-03-12','讲师','电子工程系');
INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART)
VALUES (825,'王萍','女','1972-05-05','助教','计算机系');
INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) 
VALUES (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,ClassNum 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。
    select * from score where Degree >=60 and Degree<=80;
5、 查询Score表中成绩为85，86或88的记录。
    select * from score where Degree =85 or Degree=86 or Degree =88;
6、 查询Student表中“95031”班或性别为“女”的同学记录。
    select * from student where ClassNum ="95031" or Ssex ="女";
7、 以Class降序查询Student表的所有记录。
	select * from student order by ClassNum desc;
8、 以Cno升序、Degree降序查询Score表的所有记录。
    select * from score order by Cno asc,Degree desc;
9、 查询“95031”班的学生人数。
    select count(1) from student where ClassNum ="95031";
10、查询Score表中的最高分的学生学号和课程号。
    select Sno,Cno from Score where Degree in(select max(Degree) from score);
11、查询‘3-105’号课程的平均分。
     select avg(Degree) from score where Cno ="3-105";
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 Cno,avg(degree) from score group by Cno having Cno like '3-%' and count(*)>5;
13、查询最低分大于70，最高分小于90的Sno列。
   select sno from score where degree>70 and degree <90;
14、查询所有学生的Sname、Cno和Degree列。
  select stu.Sname,s.Cno,s.Degree from student stu,score s where stu.Sno=s.Sno;
15、查询所有学生的Sno、Cname和Degree列。
  select stu.Sno,c.Cname,s.Degree from student stu,course c,score s where stu.Sno = s.Sno and c.Cno = s.Cno;
16、查询所有学生的Sname、Cname和Degree列。
  select stu.Sname,c.Cname,s.Degree from student stu,course c,score s where stu.Sno = s.Sno and c.Cno = s.Cno;
17、查询“95033”班所选课程的平均分。
select s.Cno,avg(s.Degree) 
from score s
inner join student stu 
on s.Sno = stu.Sno 
where stu.ClassNum="95033" 
group by s.Cno;
18、假设使用如下命令建立了一个grade表：

create table grade(low number(3,0),upp number(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’);
commit;
现查询所有同学的Sno、Cno和rank列。
	select s.Sno,sc.Cno,sc.Degree,
     CASE
           WHEN sc.Degree>=90 and sc.Degree<=100 THEN 'A'
           WHEN sc.Degree>=80 AND sc.Degree<=89 THEN 'B'
           WHEN sc.Degree>=70 AND sc.Degree<=79  THEN 'C'
           WHEN sc.Degree <=60 and sc.Degree<=69 THEN 'D'
   ELSE 'E'
       END as "rank"
from student s
inner join score sc
on sc.Sno =s.sno

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 stu.Sno,stu.Sname,stu.Ssex ,s.Cno,s.Degree from student stu,score s where s.Sno=stu.Sno and s.Cno="3-105" and s.Degree >(select Degree from score where Sno="109" and Cno="3-105")

20、查询score中选学一门以上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 a.cno=b.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 cno ="3-105" and 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 s.Sno,s.Sname,s.Ssex,sc.Degree,t.Tno,t.Tname
from student s
inner join score sc
on s.Sno = sc.Sno
inner join course c
on sc.Cno =c.Cno
inner join teacher t
on t.Tno =c.Tno
where t.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 t.Tno,t.Tname
from teacher t,course c
where c.Tno=t.Tno and c.Cno in(select Cno from score group by Cno having count(Cno)>5)
25、查询95033班和95031班全体学生的记录。
select s.Sno,s.Sname,sc.Degree,s.ClassNum
from student s
inner join score sc
on s.Sno=sc.Sno
where s.ClassNum in(95033,95031)
26、查询存在有85分以上成绩的课程Cno.
select s.Cno,s.Degree
from score s
where s.Degree>85
27、查询出“计算机系“教师所教课程的成绩表。
select s.Sno,s.Sname,s.ClassNum,c.Cname,sc.Degree
from student s
inner join score sc
on sc.Sno=s.Sno
inner join course c
on sc.Cno =c.Cno 
inner join teacher t
on t.Tno =c.Tno
where  t.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 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。
select Sno,Cno,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.

select Sno,Cno,Degree 
from score 
where Cno="3-105" and Degree > any(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 as name,Ssex as sex ,Sbirthday as birthday from student union select Tname as name,Tsex as sex ,Tbirthday as birthday 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 as name,Tsex as sex ,Tbirthday as birthday 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 sc.Sno,sc.Degree
from score sc
where Degree <(select avg(Degree)from score b where sc.Cno=b.Cno)

34、查询所有任课教师的Tname和Depart.
select t.Tname,t.Depart
from teacher t,course c
where t.Tno= c.Tno

35 查询所有未讲课的教师的Tname和Depart. 
	
select Tname ,Depart from teacher where Tname not in(select t.Tname from teacher t,course c where t.Tno= c.Tno)
36、查询至少有2名男生的班号。
select s.ClassNum
from student s
group by s.ClassNum
having count(s.Ssex="男")>=2
37、查询Student表中不姓“王”的同学记录。
select * from student where Sno not in(select Sno from student where Sname 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 ClassNum desc,Sbirthday asc
41、查询“男”教师及其所上的课程。

select t.Tname,t.Tsex,c.Cname
from teacher t
inner join course c
on t.Tno =c.Tno
where t.Tsex="男"
42、查询最高分同学的Sno、Cno和Degree列。
select s.Sno,c.Cno,sc.Degree
from student s
inner  join score sc
on s.Sno=sc.Sno
inner join course c
on c.Cno =sc.Cno
where Degree in
(select max(Degree) from score group by Cno )
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 ClassNum =(select ClassNum 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 s.Sno,s.Sname,s.Ssex,c.Cname,sc.Degree
from student s
inner join score sc
on sc.Sno=s.Sno
inner join course c
on c.Cno=sc.Cno
where s.Ssex="男" and c.Cname ="计算机导论"

这里不在显示结果，上面的语句有些有问题，所以自己写的时候小心，答案仅供参考~接下来，以题为例
27、查询出“计算机系“教师所教课程的成绩表。

分析为什么这样写，完整套路自己可以模仿
首先看下需求查询出“计算机系“教师所教课程的成绩表。
**
1.查什么？成绩
查 select 安排，成绩 degree
2.从哪里查？
degree在score表上
所以select degree from score
3.限制条件？（重中之重，这步分析不好基本做不出来）
计算机系“教师所教课程
计算机系在那个表，课程在那个表，搞清，**


可以看出计算机是在teacher表上，并且我们要根据tno在course上找到教的课程最后在student表上找。ok
可以一步一步来，先在teacher表上找到属于计算机系老师tno跟course对应
select tno from teacher where depart =“计算机系”
tno知道了，接下来在课程表找到对应课程名字与score表连接
select cno from course where tno in(范围)
**我知道in我没写过，这表示的是结果是一个集合有确定的数，我们只是其中一个，三部曲结束连接就行了。**好好练就完事了，一步一步分析！！

这里可能比较绕建议去看看前几层，不慌，慢慢来~编写不易，且看且点赞，万水千山总是情，点个关注行不行！