1）.创建数据库
create database学生选课数据库
2）.创建四张表
Create table Student
(
Sno Char(3) not null primary key, #学号
Sname Char(8) not null, #学生姓名
Ssex Char(2) not null, #学生姓名
Sbirthday date, #学生出生年月
Class Char(5) #学生所在班级
);
Create table Course
(
Cno Char(5) not null primary key, #课程号
Cname Varchar(10) not null, #课程名称
Tno Char(3) not null #教工编号
);
Create table Score
(
Sno Char(3) not null references Student(Sno) , #学号
Cno Char(5) not null references Course(Cno), #课程号
Degree Decimal(4,1) #成绩
);
create table Teacher
(
Tno Char(3) not null primary key, #教工编号
Tname Char(4) not null, #教工姓名
Tsex Char(2) not null, #教工性别
Tbirthday date, #教工出生年月
Prof Char(6), #职称
Depart Varchar(10) not null #教工所在部门
);
3）分别给四张表插入数据
insert into Student values('108','曾华','男','1977-09-01','95033');
insert into Student values('105','匡明','男','1975-10-02','95031');
insert into Student values('107','王丽','女','1976-01-23','95033');
insert into Student values('101','李军','男','1976-02-20','95033');
insert into Student values('109','王芳','女','1975-02-10','95031');
insert into Student values('103','陆君','男','1974-06-03','95031');
或者一句话：
insert into Student values('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')；
insert into Course values('3-105','计算机导论','825');
insert into Course values('3-245','操作系统','804');
insert into Course values('6-166','数字电路','856');
insert into Course values('9-888','高等数学','831');
或者一句话
insert into Course values('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');
insert into Score values('103','3-245','86');
insert into Score values('105','3-245','75');
insert into Score values('109','3-245','68');
insert into Score values('103','3-105','92');
insert into Score values('105','3-105','88');
insert into Score values('109','3-105','76');
insert into Score values('101','3-105','64');
insert into Score values('107','3-105','91');
insert into Score values('108','3-105','78');
insert into Score values('101','6-166','85');
insert into Score values('107','6-166','79');
insert into Score values('108','6-166','81');
或者一句话
insert into Score values('103','3-245','86'),('105','3-245','75'),('109','3-245','68'),('103','3-105','92'),('105','3-105','88'),('109','3-105','76'),('107','3-105','91'),('108','3-105','78'),('101','6-166','85'),('107','6-166','79'),('108','6-166','81');
insert into Teacher values('804','李诚','男','1958-12-02','副教授','计算机系');
insert into Teacher values('856','张旭','男','1969-03-12','讲师','电子工程系');
insert into Teacher values('825','王萍','女','1972-05-05','助教','计算机系');
insert into Teacher values('831','刘冰','女','1977-08-14','助教','电子工程系');
或者一句话
insert into Teacher values('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');
题目和答案：
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;
select depart from teacher group by depart;
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 between 60 and 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
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(Sno) from Student where class='95031';
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）
select Sno as '学号',Cno as "课程号" from Score where Degree=(select max(Degree) from Score);
11、 查询每门课的平均成绩。
select 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。
select avg(Degree) from Score group by Cno having count(Cno)>=5 and Cno like '3%'；
select avg(Degree) from Score group by Cno having count(*)>=5 and Cno like '3%'；
select avg(Degree) from Score where Cno like '3%' and Cno in (select Cno from Score group by Cno having count(*)>=5)；
（自己）Select cno,count(sno),avg(degree) from score where cno like "3%" group by cno having count(sno)>=5;
13、查询分数大于70，小于90的Sno列。
select Sno from Score where Degree between 70 and 90；（包含70和90）
select sno from score where degree >70 and degree<90;（不包含70和90）
14、查询所有学生的Sname、Cno和Degree列。
select Student.Sname,Score.Cno,Score.Degree from Student,Score where
Student.Sno=Score.Sno；
select sname,cno,degree from student join score on Student.Sno=Score.Sno；
15、查询所有学生的Sno、Cname和Degree列。
select Score.Sno,Course.Cname,Score.Degree from Score,Course where Course.Cno=Score.Cno；
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 Student.Sname,Course.Cname,Score.Degree from Student,Course,Score where Student.Sno=Score.Sno and Course.Cno=Score.Cno
select Sname,Cname,Degree from Course join Score on Course.Cno=Score.Cno join Student on Student.Sno=Score.Sno
17、查询“95033”班学生的平均分。
select avg(Degree) from Score,Student where Student.Sno=Score.Sno and class='95033'
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 Score.Sno,Score.Cno,grade.rank from score,grade where degree between low and upp #order by rank;
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 Student,Score where Student.Sno=Score.Sno and Cno='3-105' and Degree>76
select distinct a.Cno,a.Sno,a.Degree from Score a,Score b where a.Cno='3-105' and a.Degree>b.Degree and b.Sno='109' and b.Cno='3-105'
select * from Score a where a.Cno='3-105' and a.degree>(select degree b from Score where Sno='109' and Cno='3-105')
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 Sno from Score group by Sno having count(*)>1;
select * from Score where Degree not in(select max(Degree) from Score group by cno) #非课程最高分
select * from Score a where Sno in(select Sno from Score group by Sno having count(*)>1) and
a.Degree not in (select max(Degree) from Score b where b.cno=a.cno) #非课程最高分
select * from Score where Sno in(select Sno from Score group by Sno having count(*)>1) and
Degree not in (select max(Degree) from Score group by sno)#非学号最高分
select * from Score where
Degree not in (select max(Degree) from Score group by sno having count(*)>1) and
Sno in(select Sno from Score group by Sno having count(*)>1)#非学号最高分
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 Sbirthday=(select Sbirthday from Student where Sno='108') #年月日全部匹配
select Sno,Sname,Sbirthday from Student where Year(Sbirthday)=(select Year(Sbirthday) from Student where Sno='108') #只匹配年
23、查询“张旭“教师任课的学生成绩。
select Degree from Score,Course,Teacher where Teacher.Tname='张旭'and Teacher.Tno=Course.Tno and Course.Cno=Score.Cno
select Degree from Score where Cno=(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,Score group by Score.Cno having count(Score.Cno)>5)
select Tname from Teacher where tno in(select tno from course where 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 * from Student where class in('95033','95031')
26、查询存在有85分以上成绩的课程Cno.
select Cno from Score where Degree in (select Degree from Score group by Cno having Degree>85)
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 distinct * from Score where Cno in (select Cno from Course where Tno in(select Tno from Teacher where Depart='计算机系'))
select distinct Score.Sno,Score.Cno,Score.Degree from Score,Course,Teacher where Score.Cno=Course.Cno and Course.Tno=Teacher.Tno and Teacher.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')
#只查出了计算机系中的记录
select Tname,Prof 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'))
#查出了计算机系和电子工程系的记录
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 Cno,Sno,Degree from Score where Cno='3-105' and Degree>any (select Degree from Score where Cno='3-245')order by Degree desc;
# any任何一个值
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 Cno,Sno,Degree from Score where Cno='3-105' and Degree>(select max(Degree) from Score where Cno='3-245') order by Degree desc
select Cno,Sno,Degree from Score where Cno='3-105' and Degree>all(select Degree from Score where Cno='3-245') #all所有值
31、查询所有教师和同学的name、sex和birthday.
select Tname as name,Tsex as sex,Tbirthday as birthday 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.
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。
select * from Score a where a.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
select Tname,Depart from Teacher where Tno in(select Tno from Course where Teacher.Tno=Course.Tno) #理解为有课就有任课
select Tname,Depart from Teacher where exists(select Tno from Course where Teacher.Tno=Course.Tno) #通常用exists里面select后面跟*
select Tname,Depart from Teacher where Tno in(select tno from course where cno in (select cno from score where cno !=0))#理解为有课并有学生选课才是有任课
select Tname,Depart from Teacher where Tno in(select tno from course where cno in (select cno from score where course.cno=score.cno))#理解为有课并有学生选课才是有任课
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)
select Tname,Depart from Teacher where not exists(select Tno from Course where Teacher.Tno=Course.Tno) #通常用exists里面select后面跟*
select Tname,Depart from Teacher where Tno not in(select tno from course where cno in (select cno from score where cno !=0))
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。
select class from Student where Ssex='男' group by class having count(Student.Ssex)>=2
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 as姓名,year(now())-year(Sbirthday) as年龄from Student
#now sysdate取现在的时间，年月日点
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 Teacher.Tname,Teacher.Tsex,Course.Cname from Teacher,Course where Teacher.Tsex='男' and Teacher.Tno=Course.Tno
select Cname 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)
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 Cno from Course where Cname='计算机导论'#fen
select Sno from Student where Ssex='男' #fen
select * 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='男')
#满足一个条件可以用‘=’，满足多个条件用‘in’，所以最好都用‘in’
