一、設有一資料庫，包括四個表：學生表（Student）、課程表（Course）、成績表（Score）以及教師資訊表（Teacher）。用SQL語句建立四個表並完成相關題目。

表（一）Student (學生表) 

表（二）Course（課程表）

表（三）Score(成績表)

表（四）Teacher(教師表)

表1-2資料庫中的資料

表（一）Student

表（二）Course

表（三）Score

表（四）Teacher

#建學生資訊表student
create table student
(
sno varchar(20) not null primary key,
sname varchar(20) not null,
ssex varchar(20) not null,
sbirthday datetime,
class varchar(20)

);
#建立教師表
create table teacher
(
tno varchar(20) not null primary key,
tname varchar(20) not null,
tsex varchar(20) not null,
tbirthday datetime,
prof varchar(20),
depart varchar(20) not null

);
#建立課程表course
create table course
(
cno varchar(20) not null primary key,
cname varchar(20) not null,
tno varchar(20) not null,
foreign key(tno) references teacher(tno)

);
#建立成績表
create table score
(
sno varchar(20) not null primary key,
foreign key(sno) references student(sno),
cno varchar(20) not null,
foreign key(cno) references course(cno),
degree decimal

);

#新增學生資訊
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');




#新增教師表
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');

#新增課程表
insert into course values('3-105','計算機導論','825');
insert into course values('3-245','作業系統','804');
insert into course values('6-166','數位電路','856');
insert into course values('9-888','高等數學','831');
#新增成績表

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('103','3-105','64');
insert into score values('105','3-105','91');
insert into score values('109','3-105','78');
insert into score values('103','6-166','85');
insert into score values('105','6-166','79');
insert into score values('109','6-166','81');
 

1、 查詢Student表中的所有記錄的Sname、Ssex和Class列。

select Sname,Ssex,Class from student
2、 查詢教師所有的單位即不重複的Depart列。

select distinct Depart fromteacher
3、 查詢Student表的所有記錄。

select *  from student
4、 查詢Score表中成績在60到80之間的所有記錄。

select *  from Score where Degree between60and 80
5、 查詢Score表中成績為85，86或88的記錄。

select *  from Score where Degree in(85,86,88)
6、 查詢Student表中“95031”班或性別為“女”的同學記錄。

select *  from Student where class='95031'orSsex='女'
7、 以Class降序查詢Student表的所有記錄。

select *  from student order by class desc
8、 以Cno升序、Degree降序查詢Score表的所有記錄。

select *  from Score order by cno asc,degree desc
9、 查詢“95031”班的學生人數。

select count(*)  fromstudentwhere class='95031'
10、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 ScorewhereDegree=(selectmax(Degree)fromScore)

select Sno,Cno  from Scoreorderby Degree desclimit 0,1
11、查詢每門課的平均成績。

select Cno,avg(degree) from Score groupbyCno
12、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) fromscorewhere Cno like '3%'andCno in(selectCno from score group byCno having count(*)>=5) 用in不用= 是因為可能會有多個

簡單寫法：selectavg(Degree)fromscore where Cno like'3%'and group by Cno havingcount(*)>=5
13、查詢分數大於70，小於90的Sno列。

select Sno from Score where degree>70 anddegree<90
14、查詢所有學生的Sname、Cno和Degree列。

select  Sname, Cno,Degree from Score , student where Score.Sno=student.Sno
15、查詢所有學生的Sno、Cname和Degree列。

select  Sno,Cname,Degree from Score , Course where Score.Cno=Course.Cno
16、查詢所有學生的Sname、Cname和Degree列。

select Sname,Cname,Degree from student,course,score where student.Sno=score.Sno and course.Cno=score.Cno  join .. on 

寫法：selectSname,Cname,Degreefromstudent join score onstudent.Sno=score.Snojoincourse on course.Cno=score.Cno
17、查詢“95033”班學生的平均分。

select avg(degree) as'class=95033'fromScore whereSno in (selectSno from  Student whereClass='95033') 　
18、 假設使用如下命令建立了一個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’)
現查詢所有同學的Sno、Cno和rank列。

select Sno,Cno,rank from Score,grade where degree between lowandupp
19、查詢選修“3-105”課程的成績高於“109”號同學成績的所有同學的記錄。

109同學，選修是3-105課的

select * from score where Cno='3-105'anddegree>(selectmax(degree )fromScore where Sno='109'andCno='3-105')

109同學，沒有選修3-105課

select * from score where Cno='3-105'anddegree>(selectmax(degree )fromScore where Sno='109')
and degree<( selectmax(degree )fromScore where sno in(selectSnofrom score group bySnohaving count(*)>1))

選了多門課程並且是這個課程下不是最高分的

select * from score a where Sno in(selectSno from score group bySno having count(*)>1)anddegree<( select max(degree )fromScore b where b.cno = a.cno)
21、查詢成績高於學號為“109”、課程號為“3-105”的成績的所有記錄。

Select * from score where degree>(selectdegreefrom Score where Sno='109'andCno='3-105')
22、查詢和學號為108、101的同學同年出生的所有學生的Sno、Sname和Sbirthday列。

select sno,sname,sbirthday  from student where year(sbirthday) = (selectyear(sbirthday)fromstudent where  sno='108')

select sno,sname,sbirthday  from student where year(sbirthday) = (selectyear(sbirthday)fromstudent where  sno='101')
23、查詢“張旭“教師任課的學生成績。

select Sno,degree from score,Course wherescore.Cno=Course.CnoandCourse.Tno= (selectTnofrom Teacher where Tname='張旭')

select degree from scorewhereCno in (selectcno from course whereTno= (selectTnofrom Teacher where Tname='張旭' ) )
24、查詢選修某課程的同學人數多於5人的教師姓名。

select Tname from Teacher,  CoursewhereTeacher.Tno=Course.TnoandCourse.Cno =(selectCnofrom Score group byCnohaving count(*)>5)

select Tname from Teacherwheretno=( select Tno fromCourse where cno=( selectCno from Score groupbyCno havingcount(*)>5 ))
25、查詢95033班和95031班全體學生的記錄。

select * from  student where  class in('95033','95031')
26、查詢存在有85分以上成績的課程Cno.

select Cno from score where degree>85
27、查詢出“計算機系“教師所教課程的成績表。

select * from course  where cno in(selectcno from course  where tnoin(selecttno from teacher where Depart='計算機系'))
28、查詢“計算 機系”與“電子工程系“不同職稱的教師的Tname和Prof。

select Tname,Prof from TeacherwhereDepart ='計算機系'andProf  notin(selectProf from Teacher whereDepart ='電子工程系')<br>union<br>selectTname,Prof from Teacherwhere Depart ='電子工程系'andProf  notin(selectProf from Teacher whereDepart ='計算機系')
29、查詢選修編號為“3-105“課程且成績至少高於選修編號為“3-245”的同學的Cno、Sno和Degree,並按Degree從高到低次序排序。
any:代表括號中任意一個成績就可以

select Cno,Sno,Degree from score where cno='3-105'anddegree >any(selectdegreefrom score where cno='3-245')order bydegree  desc
30、查詢選修編號為“3-105”且成績高於選修編號為“3-245”課程的同學的Cno、Sno和Degree.

all:代表括號中的所有成績
select Cno,Sno,Degree from score where cno='3-105'anddegree >all(selectdegreefrom score where cno='3-245')order bydegree desc
31、查詢所有教師和同學的name、sex和birthday.

select tname,tsex,tbirthday from Teacher union selectsname,ssex,sbirthdayfromStudent
32、查詢所有“女”教師和“女”同學的name、sex和birthday.

select Tname,Tsex,Tbirthday from Teacher where Tsex='女'unionselect Sname,Ssex,Sbirthdayfrom Student where Ssex='女'
33、查詢成績比該課程平均成績低的同學的成績表。

select * from score a  where degree < (selectavg(degree)fromscore b where b.cno=a.cno)
34、查詢所有任課教師的Tname和Depart.

select Tname,Depart from Teacher where tnoin(selecttnofrom course )
35、查詢所有未講課的教師的Tname和Depart.

select Tname,Depart from Teacher where Tnonotin (selectTno from Course wherecno in (selectcno from score  ))
36、查詢至少有2名男生的班號。

select class from studentwheressex='男'groupby class havingcount(*)>1
37、查詢Student表中不姓“王”的同學記錄。

select * from Student where Sname not like'王%%'
38、查詢Student表中每個學生的姓名和年齡。

select Sname, year(now())-year(sbirthday) fromStudent
39、查詢Student表中最大和最小的Sbirthday日期值。

select Max(Sbirthday ),Min(Sbirthday )fromStudent
40、以班號和年齡從大到小的順序查詢Student表中的全部記錄。

select * from Student  order by  class desc, Sbirthday
41、查詢“男”教師及其所上的課程。

select Tname,Cname from course,teacher where course.tno= teacher.tno and teacher.Tsex='男'
42、查詢最高分同學的Sno、Cno和Degree列。

select Sno,Cno,Degree from score where degree=(selectmax(degree)fromscore)

排序寫法：select Sno,Cno,Degree from score order bydegreedesc limit 0,1

43、查詢和“李軍”同性別的所有同學的Sname.

select Sname from StudentwhereSsex = (selectSsexfrom Student where Sname='李軍')
44、查詢和“李軍”同性別並同班的同學Sname.

select Sname from StudentwhereSsex = (selectSsexfrom Student where Sname='李軍')and class=( select classfromstudent where Sname='李軍')
45、查詢所有選修“計算機導論”課程的“男”同學的成績表。

select Sno,Cno,degree from score where Cno=(selectCno from course whereCname='計算機導論')andSno in(selectSno from student where Ssex='男')