一、创建数据表
1. 创建学生表“students”：
create table students
(sno varchar(3) not null,
sname varchar(4) not null,
ssex varchar(2) not null,
sbirthday datetime,
class varchar(5))
2. 创建课程表“courses”：
create table courses
(cno varchar(5) not null,
cname varchar(10) not null,
tno varchar(10) not null)
3. 创建成绩表“scores”：
create table scores
(sno varchar(3) not null,
cno varchar(5) not null,
degree numeric(10, 1) not null)
4. 创建教师表“teachers”：
create table teachers
(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)
二、 表中插入数据
1. students表中插入数据：
insert into students(sno,sname,ssex,sbirthday,class) values (108 ,'曾华' ,'男' ,'1977-09-01',95033);
insert into students(sno,sname,ssex,sbirthday,class) values (105 ,'匡明' ,'男' ,'1975-10-02',95031);
insert into students(sno,sname,ssex,sbirthday,class) values (107 ,'王丽' ,'女' ,'1976-01-23',95033);
insert into students(sno,sname,ssex,sbirthday,class) values (101 ,'李军' ,'男' ,'1976-02-20',95033);
insert into students(sno,sname,ssex,sbirthday,class) values (109 ,'王芳' ,'女' ,'1975-02-10',95031);
insert into students(sno,sname,ssex,sbirthday,class) values (103 ,'陆君' ,'男' ,'1974-06-03',95031);
2. courses表中插入数据：
insert into courses(cno,cname,tno) values ('3-105' ,'计算机导论',825);
insert into courses(cno,cname,tno) values ('3-245' ,'操作系统' ,804);
insert into courses(cno,cname,tno) values ('6-166' ,'数据电路' ,856);
insert into courses(cno,cname,tno) values ('9-888' ,'高等数学' ,100);
3. scores表中插入数据：
insert into scores(sno,cno,degree) values (103,'3-245',86);
insert into scores(sno,cno,degree) values (105,'3-245',75);
insert into scores(sno,cno,degree) values (109,'3-245',68);
insert into scores(sno,cno,degree) values (103,'3-105',92);
insert into scores(sno,cno,degree) values (105,'3-105',88);
insert into scores(sno,cno,degree) values (109,'3-105',76);
insert into scores(sno,cno,degree) values (101,'3-105',64);
insert into scores(sno,cno,degree) values (107,'3-105',91);
insert into scores(sno,cno,degree) values (108,'3-105',78);
insert into scores(sno,cno,degree) values (101,'6-166',85);
insert into scores(sno,cno,degree) values (107,'6-106',79);
insert into scores(sno,cno,degree) values (108,'6-166',81);
4. teachers表中插入数据：
insert into teachers(tno,tname,tsex,tbirthday,prof,depart) values (804,'李诚','男','1958-12-02','副教授','计算机系');
insert into teachers(tno,tname,tsex,tbirthday,prof,depart) values (856,'张旭','男','1969-03-12','讲师','电子工程系');
insert into teachers(tno,tname,tsex,tbirthday,prof,depart) values (825,'王萍','女','1972-05-05','助教','计算机系');
insert into teachers(tno,tname,tsex,tbirthday,prof,depart) values (831,'刘冰','女','1977-08-14','助教','电子工程系');
三、开始做题
1. 查询students表中的所有记录的sname、ssex和class列：
select sname,ssex,class
from students;
结果输出：
2. 查询教师所有的单位，即不重复的depart列：
select distinct depart
from teachers;
结果输出：
3. 查询students表的所有记录：
select *
from students;
结果输出：
4. 查询scores表中成绩在60到80之间的所有记录：
select *
from scores
where degree between 60 and 80;
结果输出：
5. 查询score表中成绩为85，86或88的记录：
select *
from scores
where degree in (85,86,88);
结果输出：
6. 查询students表中“95031”班或性别为“女”的同学记录：
select *
from students
where class = '95031' or ssex = '女';
结果输出：
7. 以class降序查询students表的所有记录：
select *
from students
order by class desc;
结果输出：
8. 以cno升序、degree降序查询scores表的所有记录：
select *
from scores
order by cno,degree desc;
结果输出：
9. 查询“95031”班的学生人数：
select class,count(1) as stunum
from students
where class = '95031';
结果输出：
10. 查询scores表中的最高分的学生学号和课程号：
select sno,cno
from scores
order by degree
limit 1;
结果输出：
11. 查询‘3-105’号课程的平均分：
select avg(degree)
from scores
where cno = '3-105';
结果输出：
12. 查询scores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 scores
where cno like '3%'
group by cno
having count(sno) >= 5;
结果输出：
13. 查询最低分大于70，最高分小于90的sno列：
方法1：
select sno
from scores
group by sno
having min(degree) > 70 and max(degree) < 90;
方法2：
select sno
from scores
group by sno
having degree between '70' and '90';
方法3：
select sno
from scores
group by sno
having max(degree) between '70' and '90' and min(degree) between '70' and '90';
结果输出：
14. 查询所有学生的sname、sno和segree列：
select sname,cno,degree
from students inner join scores
on scores.sno = students.sno
order by sname;
结果输出：
15. 查询所有学生的sno、sname和segree列：
select sno,cname,degree
from scores inner join courses
on scores.cno = courses.cno
order by sno;
结果输出：
16. 查询所有学生的sname、cname和degree列：
select sname,cname,degree
from students inner join scores
on students.sno = scores.sno
inner join courses
on scores.cno = courses.cno
order by sname;
结果输出：
17. 查询“95033”班所选课程的平均分：
select courses.cno,cname,avg(degree)
from students inner join scores
on students.sno = scores.sno
inner join courses
on scores.cno = courses.cno
where class = '95033'
group by courses.cno
order by courses.cno
结果输出：
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');
commit;
现查询所有同学的sno、cno和rank列：
select sno,cno,rank
from scores inner join grade
on (scores.degree >= grade.low and scores.degree <= grade.upp)
order by sno;
结果输出：
19. 查询选修“3-105”课程同学的成绩高于“109”号同学成绩的所有同学的记录：
select s1.sno,s1.degree
from scores as s1 inner join scores as s2
on (s1.cno = s2.cno and s1.degree > s2.degree)
where s1.cno = '3-105' and s2.sno = '109'
order by s1.sno;
结果输出：
20. 查询scores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：
方法1：
select *
from scores
group by sno
having count(cno)>1 and degree != max (degree);
方法2：
select a.*
from scores a
where a.degree<(select max(degree)
from scores b
where a.sno=b.sno)；
结果输出：
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：
方法1：
select sno,degree
from scores
where degree >
(select max(degree)
from scores
where sno = 109)
and cno = '3-105';
方法2：
select s1.sno,s1.degree
from scores as s1 inner join scores as s2
on (s1.cno = s2. cno and s1.degree > s2.degree)
where s1.cno = '3-105' and s2.sno = '109'
order by s1.sno;
结果输出：
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：
方法1：
select sno,sname,sbirthday
from students
where year(sbirthday) = (
select year(sbirthday)
from students
where sno = '108'
);
方法2：
select s1.sno,s1.sname,s1.sbirthday
from students s1 join students s2
on year(s1.sbirthday) = year(s2.sbirthday)
where s2.sno = '108';
结果输出：
23. 查询“张旭“教师任课的学生成绩：
select sno,degree
from scores join courses
on scores.cno = courses.cno join teachers
on courses.tno = teachers.tno
where tname = '张旭';
结果输出：
24. 查询选修某课程的同学人数多于5人的教师姓名：
select distinct tname
from scores join courses
on scores.cno = courses.cno join teachers
on courses.tno = teachers.tno
group by scores.cno
having count(scores.sno)>5;
结果输出：
25. 查询95033班和95031班全体学生的记录：
select *
from students
where class in ('95033','95031')
order by class;
结果输出：
26. 查询存在有85分以上成绩的课程cno：
select distinct cno
from scores
where degree > 85;
结果输出：
27. 查询出“计算机系“教师所教课程的成绩表：
select tname,scores.cno,sno,degree
from scores join courses on scores.cno = courses.cno
join teachers on courses.tno = teachers.tno
where depart = '计算机系'
order by tname,scores.cno,sno,degree desc;
结果输出：
28. 查询“计算机系”职称与“电子工程系“职称不同的教师的tname和prof：
select tname,prof
from teachers
where depart = '计算机系' and prof not in (
select distinct prof
from teachers
where depart = '电子工程系'
);
结果输出：
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 scores
where cno = '3-105' and degree > any(
select degree
from scores
where cno = '3-245')
order by degree desc;
结果输出：
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 scores
where cno = '3-105' and degree > all(
select degree
from scores
where cno = '3-245')
order by degree desc;
结果输出：
31. 查询所有教师和同学的name、sex和birthday：
select sname,ssex,sbirthday
from students
union
select tname,tsex,tbirthday
from teachers;
结果输出：
32. 查询所有“女”教师和“女”同学的name、sex和birthday：
select sname,ssex,sbirthday
from students
where ssex = '女'
union
select tname,tsex,tbirthday
from teachers
where tsex = '女';
结果输出：
33. 查询成绩比该课程平均成绩低的同学的成绩表：
select s1.*
from scores as s1 inner join (
select cno,avg(degree) as adegree
from scores
group by cno) as s2
on (s1.cno = s2.cno and s1.degree < s2.adegree);
结果输出：
34. 查询所有任课教师的tname和depart：
方法1：
select tname,depart
from teachers left join courses
on teachers.tno = courses.tno
where cno is not null;
方法2：
select tname,depart
from teachers
where tno in (
select tno
from courses
);
结果输出：
35. 查询所有未讲课的教师的tname和depart：
方法1：
select tname,depart
from teachers left join courses
on teachers.tno = courses.tno
where cno is null;
方法2：
select tname,depart
from teachers
where tno not in (
select tno
from courses
);
结果输出：
36. 查询至少有2名男生的班号：
select class
from students
group by class
having count(ssex = '男')>=2;
结果输出：
37. 查询students表中不姓“王”的同学记录：
select *
from students
where sname not like '王%';
结果输出：
38. 查询students表中每个学生的姓名和年龄：
select sname,year(now())-year(sbirthday) as sage
from students
order by sage;
结果输出：
39. 查询student表中最大和最小的sbirthday日期值：
select max(sbirthday),min(sbirthday)
from students;
结果输出：
40. 以班号和年龄从大到小的顺序查询students表中的全部记录：
select *
from students
order by class desc, sbirthday asc;
结果输出：
41. 查询“男”教师及其所上的课程：
select tname,cname
from teachers join courses
on teachers.tno = courses.tno
where tsex = '男';
结果输出：
42. 查询最高分同学的sno、cno和degree列：
select *
from scores
group by cno
having degree = max(degree);
结果输出：
43. 查询和“李军”同性别的所有同学的sname：
方法1：
select sname
from students
where ssex =
(select ssex
from students
where sname = '李军');
方法2：
select s1.sname
from students as s1 inner join students as s2
on s1.ssex = s2.ssex
where s2.sname = '李军';
结果输出：
44. 查询和“李军”同性别并同班的同学sname：
select s1.sname
from students s1 join students s2
on s1.ssex = s2.ssex and s1.class = s2.class
where s2.sname = '李军';
结果输出：
45. 查询所有选修“计算机导论”课程的“男”同学的成绩表：
select scores.sno,degree
from students join scores
on students.sno = scores.sno join courses
on scores.cno = courses.cno
where cname = '计算机导论' and ssex = '男'
order by sno;
结果输出：