數據庫——練習題答案

create database 學生選課數據庫
Create table Student
(
Sno Char(3) not null primary key, #學號
Sname Char(8) not null, #學生姓名
Ssex Char(2) not null, #學生姓名
Sbirthday datetime, #學生出生年月
Class Char(5) #學生所在班級
);

Create table Course
(
Cno Char(5) not null primary key, #課程號
Cname Varchar(10) not null, #課程名稱
Tno Char(3) not null #教工編號
);
Create table Score
(
Sno Char(3) not null references Student(Sno) , #學號
Cno Char(5) not null references Course(Cno), #課程號
Degree Decimal(4,1) #成績
);

create table Teacher
(
Tno Char(3) not null primary key, #教工編號
Tname Char(4) not null, #教工姓名
Tsex Char(2) not null, #教工性別
Tbirthday datetime, # 教工出生年月
Prof Char(6), #職稱
Depart Varchar(10) not null #教工所在部門

);

insert into Student values('108','曾華','男','1977-09-01','95033');
insert into Student values('105','匡明','男','1975-10-02','95031');
insert into Student values('107','王麗','女','1976-01-23','95033');
insert into Student values('101','李軍','男','1976-02-20','95033');
insert into Student values('109','王芳','女','1975-02-10','95031');
insert into Student values('103','陸君','男','1974-06-03','95031');

insert into Course values('3-105','計算機導論','825');
insert into Course values('3-245','操做系統','804');
insert into Course values('6-166','數字電路','856');
insert into Course values('9-888','高等數學','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');

insert into Teacher values('804','李誠','男','1958-12-02','副教授','計算機系');
insert into Teacher values('856','張旭','男','1969-03-12','講師','電子工程系');
insert into Teacher values('825','王萍','女','1972-05-05','助教','計算機系');
insert into Teacher values('831','劉冰','女','1977-08-14','助教','電子工程系');

一、查詢Student表中的全部記錄的Sname、Ssex和Class列。
select Sname,Ssex,Class from Student

二、 查詢教師全部的單位即不重複的Depart列。
select distinct Depart from Teacher

三、 查詢Student表的全部記錄。
select * from Student

四、 查詢Score表中成績在60到80之間的全部記錄。
select * from Score where Degree between 60 and 80

五、 查詢Score表中成績爲85，86或88的記錄。
select * from Score where Degree=85 or Degree=86 or Degree=88

select * from Score where Degree in (85,86,88)

六、 查詢Student表中「95031」班或性別爲「女」的同窗記錄。
select * from Student where class='95031' or Ssex='女'

七、 以Class降序查詢Student表的全部記錄。
select * from student order by class desc

八、 以Cno升序、Degree降序查詢Score表的全部記錄。
select * from Score order by Cno, Degree desc

九、 查詢「95031」班的學生人數。
select count(Sno) from Student where class='95031'

select count(*) from Student where class='95031'

十、?查詢Score表中的最高分的學生學號和課程號。（子查詢或者排序）
select Sno,Cno from Score where Degree=(select max(Degree) from Score)

十一、 查詢每門課的平均成績。
select avg(Degree) from Score where Cno='3-245';
select avg(Degree) from Score where Cno='3-105';
select avg(Degree) from Score where Cno='6-166';

select avg(Degree) from Score group by Cno;

十二、查詢Score表中至少有5名學生選修的並以3開頭的課程的平均分數。
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)

1三、查詢分數大於70，小於90的Sno列。
select Sno from Score where Degree between 70 and 90

1四、查詢全部學生的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

1五、查詢全部學生的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

1六、查詢全部學生的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

1七、 查詢「95033」班學生的平均分。
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')
1八、 假設使用以下命令創建了一個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');
現查詢全部同窗的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

1九、  查詢選修「3-105」課程的成績高於「109」號同窗成績的全部同窗的記錄。
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、查詢score中選學多門課程的同窗中分數爲非最高分紅績的記錄。
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) #非課程最高分

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) #非課程最高分

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)#非學號最高分

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)#非學號最高分

2一、 查詢成績高於學號爲「109」、課程號爲「3-105」的成績的全部記錄。
select * from Score where degree>(select degree from Score where Sno='109' and Cno='3-105')

2二、查詢和學號爲108的同窗同年出生的全部學生的Sno、Sname和Sbirthday列。
select Sno,Sname,Sbirthday from Student where Sbirthday=(select Sbirthday from Student where Sno='108') #年月日所有匹配

select Sno,Sname,Sbirthday from Student where Year(Sbirthday)=(select Year(Sbirthday) from Student where Sno='108') #只匹配年

2三、查詢「張旭「教師任課的學生成績。
select Degree from Score,Course,Teacher where Teacher.Tname='張旭'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='張旭'))

2四、查詢選修某課程的同窗人數多於5人的教師姓名。

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))
2五、查詢95033班和95031班全體學生的記錄。
select * from Student where class in('95033','95031')

2六、查詢存在有85分以上成績的課程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
2七、查詢出「計算機系「教師所教課程的成績表。
select distinct * from Score where Cno in (select Cno from Course where Tno in(select Tno from Teacher where Depart='計算機系'))

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='計算機系'

2八、查詢「計算機系」與「電子工程系「不一樣職稱的教師的Tname和Prof。
select Tname,Prof from Teacher where Depart='計算機系' and prof not in (select Prof from Teacher where Depart='電子工程系')
#只查出了計算機系中的記錄

select Tname,Prof from Teacher where Prof not in (select Prof from Teacher where Depart='計算機系' and prof in (select Prof from Teacher where Depart='電子工程系'))
#查出了計算機系和電子工程系的記錄

2九、查詢選修編號爲「3-105「課程且成績至少高於選修編號爲「3-245」的同窗的Cno、Sno和Degree,並按Degree從高到低次序排序。
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 任何一個值

30、查詢選修編號爲「3-105」且成績高於選修編號爲「3-245」課程的同窗的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 全部值

3一、 查詢全部教師和同窗的name、sex和birthday.
select Tname as name,Tsex as sex,Tbirthday as birthday from Teacher union select Sname,Ssex,Sbirthday from Student

3二、查詢全部「女」教師和「女」同窗的name、sex和birthday.
select Tname,Tsex,Tbirthday from Teacher where Tsex='女' union select Sname,Ssex,Sbirthday from Student where Ssex='女'

3三、 查詢成績比該課程平均成績低的同窗的成績表。
select * from Score a where a.Degree<(select avg(Degree) from Score b where b.Cno=a.Cno)

3四、 查詢全部任課教師的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) #理解爲有課就有任課

select Tname,Depart from Teacher where exists(select Tno from Course where Teacher.Tno=Course.Tno) #一般用exists裏面select後面跟*

select Tname,Depart from Teacher where Tno in(select tno from course where cno in (select cno from score where cno !=0))#理解爲有課並有學生選課纔是有任課

select Tname,Depart from Teacher where Tno in(select tno from course where cno in (select cno from score where course.cno=score.cno))#理解爲有課並有學生選課纔是有任課

35 、 查詢全部未講課的教師的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) #一般用exists裏面select後面跟*

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))

3六、查詢至少有2名男生的班號。
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

3七、查詢Student表中不姓「王」的同窗記錄。
select * from Student where Sname not like '王%'

3八、查詢Student表中每一個學生的姓名和年齡。
select Sname as 姓名,year(now())-year(Sbirthday) as 年齡 from Student
#now sysdate 取如今的時間，年月日點

3九、查詢Student表中最大和最小的Sbirthday日期值。
select max(Sbirthday),min(Sbirthday) from Student

40、以班號和年齡從大到小的順序查詢Student表中的所有記錄。
select * from Student order by class desc,Sbirthday

4一、查詢「男」教師及其所上的課程。
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')

4二、查詢最高分同窗的Sno、Cno和Degree列。
select * from Score where Degree=(select max(Degree) from Score)

4三、查詢和「李軍」同性別的全部同窗的Sname.
select Sname from Student where Ssex=(select Ssex from Student where Sname='李軍')

4四、查詢和「李軍」同性別並同班的同窗Sname.
select Sname from Student where Ssex=(select Ssex from Student where Sname='李軍') and class=(select class from Student where Sname='李軍')

4五、查詢全部選修「計算機導論」課程的「男」同窗的成績表。
select Cno from Course where Cname='計算機導論'#fen
select Sno from Student where Ssex='男' #fen

select * from Score
where Cno in (select Cno from Course where Cname='計算機導論') and Sno in (select Sno from Student where Ssex='男')

#知足一個條件能夠用‘=’，知足多個條件用‘in’，因此最好都用‘in’