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)

);
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');

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

);
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');


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)

);
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');


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

);
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('101','3-105','92');
insert into score values('107','3-105','88');
insert into score values('108','3-105','76');

insert into score values('109','3-105','64');
insert into score values('104','3-105','91');
insert into score values('100','3-105','78');
insert into score values('102','6-166','85');
insert into score values('104','6-166','79');
insert into score values('109','6-166','81');
select * from score

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 from teacher
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 BETWEEN 60 and 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' or ssex='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(*) from student where 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 score where degree=(select max(degree) from score)
--方式二
SELECT sno,cno from score ORDER BY degree desc limit 1
11、     查詢每門課的平均成績。
select cno,avg(degree) from score GROUP BY cno
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) from score where cno like '3%' and cno in(
select cno from score group by cno having count(*)>=5)
--方式二：
select avg(degree) from score where cno like '3%'  group by cno having count(*)>=5
13、     查詢分數大於70，小於90的Sno列。
select sno from score where degree>70 and degree<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 s,course c where s.cno=c.cno
16、     查詢所有學生的Sname、Cname和Degree列。
select sname,degree from student s,course c,score sc where s.sno=sc.sno and c.cno=sc.cno
--使用join....on方式
select sname,cname,degree from student s join score  sc on s.sno=sc.sno join course c on sc.cno=c.cno
17、     查詢“95033”班學生的平均分。
select avg(degree) as avgdegree from score where sno in(select sno from student where class='95033')
18、 假設使用如下命令建立了一個grade表：
drop table grade
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');
select * from grade
SELECT * from score
現查詢所有同學的Sno、Cno和rank列。
select score.sno,score.cno,grade.rank  from score,grade where score.degree BETWEEN grade.low and grade.upp
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。
select * from score where cno='3-105' and degree>(
select max(degree) from score where sno='109' and cno='3-105'
)
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>(
select degree from score where sno='109' and cno='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)=(
select year(sbirthday) from student where sno='108'
)
23、查詢“張旭“教師任課的學生成績。
select sno,degree from score s,course c where s.cno=c.cno and c.tno=(
select tno from teacher where tname='張旭'
)
--方式二
select degree from score where cno in(
select cno from course where tno=(
select tno from 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 t,course c where t.tno=c.tno and c.cno=(
select cno from score GROUP BY cno HAVING count(*)>5
)
--方式二
select tname from teacher where tno=(
select tno from course where cno=(
select cno from score GROUP BY cno HAVING count(*)>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(select cno from course where tno in(
select tno 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 teacher where depart='計算機系' and prof not in(
select prof from teacher where depart='電子工程系'
)
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' and degree>any(
select degree from score where cno='3-245'
)ORDER BY degree 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' and degree>all(
select degree from score where cno='3-245'
)ORDER BY degree desc
31、 查詢所有教師和同學的name、sex和birthday.
select tname,tsex,tbirthday from teacher union select sname,ssex,sbirthday from student
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' union select sname,ssex,sbirthday from 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<(select avg(degree) from score 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 tno in(
select tno from course
)
35 、 查詢所有未講課的教師的Tname和Depart.
select tname,depart from teacher where tno not in(
select tno from course where cno in(
select cno from score
)
)
36、查詢至少有2名男生的班號。
select class from student where ssex='男' GROUP BY class HAVING count(*)>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) from student
39、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表中的全部記錄。
select * from student ORDER BY class desc,sbirthday desc
41、查詢“男”教師及其所上的課程。
select tname,cname from course c,teacher t where c.tno=t.tno and t.tsex='男'
42、查詢最高分同學的Sno、Cno和Degree列。
select sno,cno,degree from score where degree=(
select max(degree) from score
)
--排序寫法
select sno,cno,degree from score ORDER BY degree desc limit 1
43、查詢和“李軍”同性別的所有同學的Sname.
select sname from student where ssex=(
select ssex from student where sname='李軍'
)
44、查詢和“李軍”同性別並同班的同學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'
)
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=(
select cno from course where cname='計算機導論'
)and sno in(select sno from student where ssex='男')