oracle子查询练习题与答案解析笔记小白练习！（内有福利）

-- from(emp) -->sum-->select

-- 创建表
-- 学生表 student
-- sno 学号、编号
-- sname 学生姓名
-- sage 年龄
-- ssex 性别
create table student(
sno varchar2(10) primary key,
sname varchar2(20),
sage number(2),
ssex varchar2(5)
);
-- 教师表 teacher
-- tno 编号
-- tname 姓名
create table teacher(
tno varchar2(10)primary key,
tname varchar2(20)
);
-- 课程表 course
-- cno 课程编号
-- cname 课程名字
-- tno 老师编号
create table course(
cno varchar2(10),
cname varchar2(20),
tno varchar2(20),
constraint pk_course primary key (cno,tno)
);
-- 分数表 sc
-- sno 学生编号
-- cno 课程编号
-- score 成绩、分数
create table sc(
sno varchar2(10),
cno varchar2(10),
score number(5,2),
constraint pk_sc primary key(sno,cno)
);
select * from student;
select * from teacher;
select * from course;
select * from sc;

--为表中添加数据
-- 学生表
insert into student values('s001','张三',23,'男');
insert into student values('s002','李四',23,'男');
insert into student values('s003','吴鹏',25,'男');
insert into student values('s004','琴沁',20,'女');
insert into student values('s005','王丽',20,'女');
insert into student values('s006','李波',21,'男');
insert into student values('s007','刘玉',21,'男');
insert into student values('s008','萧蓉',21,'女');
insert into student values('s009','陈萧晓',23,'女');
insert into student values('s010','陈美',22,'女');
commit;

-- 老师表
insert into teacher values('t001','刘阳');
insert into teacher values('t002','谌燕');
insert into teacher values('t003','胡明星');
commit;

-- 课程表
insert into course values('c001','J2SE','t002');
insert into course values('c002','Java Web','t002');
insert into course values('c003','SSH','t001');
insert into course values('c004','Oracle','t001');
insert into course values('c005','SQL SERVER 2005','t003');
insert into course values('c006','C#','t003');
insert into course values('c007','JavaScript','t002');
insert into course values('c008','DIV+CSS','t001');
insert into course values('c009','PHP','t003');
insert into course values('c010','EJB3.0','t002');
commit;
-- 成绩表
insert into sc values('s001','c001','78.9');
insert into sc values('s002','c001','80.9');
insert into sc values('s003','c001','81.9');
insert into sc values('s004','c001','60.9');
insert into sc values('s001','c002','82.9');
insert into sc values('s002','c002','72.9');
insert into sc values('s003','c002','81.9');
insert into sc values('s001','c003','59');
commit;
----------------------------------------------------------
-- 统计学生表男生和女生的人数
select
sum(case when ssex='男' then 1 else 0 end) 男生人数,
sum(case when ssex='女' then 1 else 0 end) 女生人数
from student;
select * from student;

select * from student;-- 学生学号学生姓名学生年龄学生性别
select * from teacher;-- 老师编号老师姓名
select * from course;-- 课程号学生姓名老师编号
select * from sc;-- 学号课程号成绩
select cno,cname from course where cno cname is not in (select cno,cname from course where tno = 't002');-- is not in （待研究）
select cno,cname from course where tno = 't002';-- 学过燕子的学生学号和姓名
select cno,cname from course;-- 全部的学生学号和姓名
select cno,cname from course minus select cno,cname from course where tno = 't002';

1、查询“c001”课程比“c002”课程成绩高的所有学生的学号；
select * from sc where cno = 'c001';
select * from sc where cno = 'c002';
select e.sno from sc e join sc m on e.sno = m.sno where e.cno = 'c001' and m.cno = 'c002' and e.score > m.score;-- 自连接
select a.sno from (select * from sc where cno = 'c001')a,(select * from sc where cno = 'c002')b where a.sno=b.sno and a.score >b.score;
-- a表，b表 where 条件
select a.sno from (select * from sc where cno = 'c001')a join (select * from sc where cno = 'c002')b on a.sno=b.sno where a.score >b.score;
-- (式子)a表 join （式子）b表 on a。（）=b。（） where条件条件设表ab （内连接）
2、查询平均成绩大于60 分的同学的学号和平均成绩；
select avg(score) from sc;
select * from sc where (select avg(score) from sc)>60;-- 平均成绩大于60的同学全部信息
select avg(score),sno from sc group by sno;-- 每个学好的平均成绩
select avg(score),sno from sc group by sno having avg(score)>60;-- 2

3、查询所有同学的学号、姓名、选课数、总成绩；
select count(*)选棵树,sno from sc group by sno;-- 课程数
select count(*)a,sum(score)b,sno from sc group by sno;-- 学号总成绩选棵树
select k.sname,t.sno,t.a,t.b from student k join (select count(*)a,sum(score)b,sno from sc group by sno)t on k.sno=t.sno;-- 3

select a.sno,k.sname,a."选棵树",b."总成绩" from student k,(select count(*)选棵树,sno from sc group by sno)a join -- 3(不对的版本)
(select sum(score)总成绩,sno from sc group by sno)b
on b.sno = a.sno;

4、查询姓“刘”的老师的个数；
select tname from teacher where tname like '刘%';
select count(*),tname from teacher group by tname having tname like '刘%';-- 4
5、查询没学过“谌燕”老师课的同学的学号、姓名；
select cno,cname from course where cno not in (select cno from course where tno = 't002');-- not in （形势正确）
select cno,cname from course where tno = 't002';-- 学过燕子的学生学号和姓名
select cno,cname from course;-- 全部的学生学号和姓名
select cno,cname from course minus select cno,cname from course where tno = 't002';-- 5
select * from student;-- 学生学号学生姓名学生年龄学生性别
select * from teacher;-- 老师编号老师姓名
select * from course;-- 课程号学生姓名老师编号
select * from sc;-- 学号课程号成绩
6、查询学过“c001”并且也学过编号“c002”课程的同学的学号、姓名；
select a.sno,a.sname from student a join sc b on a.sno=b.sno where cno='c001'
intersect -- 6
select a.sno,a.sname from student a join sc b on a.sno=b.sno where cno='c002';

7、查询学过“谌燕”老师所教的所有课的同学的学号、姓名；
select cno,cname from course where tno = 't002';-- 学过燕子的学生学号和姓名
select cno,cname from course;-- 全部的学生学号和姓名
select cno,cname from course minus select cno,cname from course where tno = 't002';
-- 先拿到她的编号 t002
select tno from teacher where tname='谌燕';

-- 根据这个老师编号去查询课程编号
select cno from course where tno =(select tno from teacher where tname='谌燕');

-- 根据课程编号去查询学过的学号
select sno from sc
where
cno =all
(select cno from course where tno =(select tno from teacher where tname='谌燕'))

-- 拿着上面查询的编号去查他的姓名
select t1.sno,sname from student t1
join(
select sno from sc
where exists
(select cno from course where tno =(select tno from teacher where tname='谌燕'))

) t2
on t1.sno=t2.sno;

-----------------------------------------------------
-- 课程编号
select cno from course where tno =(
select tno from teacher where tname='谌燕');
-- 这个老师带的课程数量 4

-- 查询学过的学号
select sno from sc where sc.cno in(
select cno from course where tno =(
select tno from teacher where tname='谌燕')
);
-- 统计学生学过的他的课程数量

select sc.sno,count(sc.cno) from sc where sc.cno in(
select cno from course where tno =
(select tno from teacher where tname='谌燕') -- 课程编号
) group by sc.sno
;

-- 学过所有课程的学号
select sc.sno,count(sc.cno) from sc where sc.cno in(
select cno from course where tno =
(select tno from teacher where tname='谌燕')
)group by sc.sno
having count(sc.cno)= (select count(*) from course where course.tno=
(select teacher.tno from teacher where teacher.tname='谌燕'));
---- 最终结果 -------第七题
select t1.sno,sname from student t1
join
(select sc.sno,count(sc.cno) from sc where sc.cno in(
select cno from course where tno =
(select tno from teacher where tname='谌燕')
)group by sc.sno
having count(sc.cno)= (select count(*) from course where course.tno=
(select teacher.tno from teacher where teacher.tname='谌燕')))t2
on t1.sno = t2.sno

8、查询课程编号“c002”的成绩比课程编号“c001”课程低的所有同学的学号、姓名；
select * from sc where cno='c002'-- c2 所有人信息
select * from sc where cno='c001'-- c1 所有人信息
select distinct k.sname,m.sno from student k right join
(select a.sno from (select * from sc where cno='c002')a,(select * from sc where cno='c001')b where a.score<b.score)m-- 8
on m.sno=k.sno;-- 8

9、查询所有课程成绩小于60 分的同学的学号、姓名；
select * from sc where score<60;
select m.sno,k.sname from student k join (select * from sc where score<60)m on k.sno=m.sno;-- 9

10、查询没有学全所有课的同学的学号、姓名；
select count(*)gg,sno from sc group by sno-- 每个学号后面学的学科数如果等于10 那就是10科全部学完了
select k.sno,k.sname from student k full join (select count(*)gg,sno from sc group by sno)b on -- join on 后面可以加where 但不建议加
k.sno=b.sno and b.gg !=10; -- 10
-- 第十题其他方法--------------------------10
-- 先统计所有课的数量
select count(*) from course;
--再查每个人学了几门课
select sc.sno,count(cno) from sc group by sno having count(cno)!=(select count(*) from course);
-- 根据学号查询对应的姓名
select k.sname,k.sno from student k full outer join (select sc.sno,count(cno) from sc group by sno having count(cno)!=(select count(*) from course)) b
on k.sno=b.sno--- 全连接方法
--
select s.sno,s.sname from student s
join
(select sno,count(cno) b from sc group by sno) k-- 第二种join on 的方法
on k.b!=(select count(cno) a from course)
---
select sno,sname from student where sno not in (
select sno from sc group by sno -- not in的方法
having count(cno)=(select count(*) from course));

11、查询至少有一门课与学号为“s001”的同学所学相同的同学的学号和姓名； select * from student;-- 学生学号学生姓名学生年龄学生性别
select * from teacher;-- 老师编号老师姓名
select * from course;-- 课程号课程名字老师编号
select * from sc;-- 学号课程号成绩
select cno from sc where sno='s001';-- c01,2,3
select sno from sc where cno in ('c001','c002','c003') and sno!='s001';-- 至少有一门课与学号为“s001”的同学所学相同的同学的学号
select distinct b.sno,k.sname from student k join (select sno from sc where cno in ('c001','c002','c003'))b-- and sno!='s001'
on k.sno = b .sno;-- 11

12、查询至少学过学号为“s001”同学所有一门课的其他同学学号和姓名；
select cno from sc where sno='s001';-- c01,2,3
select sno from sc where cno in ('c001','c002','c003') and sno!='s001';-- 至少有一门课与学号为“s001”的同学所学相同的同学的学号
select distinct b.sno,k.sname from student k join (select sno from sc where cno in ('c001','c002','c003') and sno!='s001')b
on k.sno = b .sno;-- 12

13、查询和“s001”号的同学学习的课程完全相同的其他同学学号和姓名
select cno from sc where sno='s001';-- c01,2,3
select sno from sc where cno in ( 'c001','c002','c003') and sno!='s001';-- 至少有一门课与学号为“s001”的同学所学相同的同学的学号
select count(cno),sno from sc where cno in ( 'c001','c002','c003') and sno!='s001' group by sno having count(cno)=3;
-- 先定义出在c01.。c03的区间，在这个区间里面再用having筛选课程数量在3个的人，只要是满足了count（cno）=3.那么所学的课程数必然一样，因为表格里面
-- 绝对没有重复数据的可能
select b.sno,k.sname from student k join (select count(cno),sno from sc where cno in ( 'c001','c002','c003') and sno!='s001' group by sno
having count(cno)=3)b on b.sno=k.sno;-- 13

14、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分
select distinct cno from sc;
select max(score),min(score),cno from sc group by cno
select k.cname,m,n from course k join (select max(score) m ,min(score) n ,cno from sc group by cno
) b on k.cno=b.cno-- 14

15、按各科平均成绩从低到高和及格率的百分数从高到低顺序
select avg(score),cno from sc group by cno order by avg(score) asc
select avg (score) hh,sc.cno,sum(case when score>=60 then 1 else 0 end) vv / count(sno) from sc-- from的前面是一个个的序列，后面并不能起别名
group by cno order by 2 asc, 3 desc-- 起别名错误示范 -- 只有结果集才可以起别名比如emp e

select avg (score),sc.cno,sum(case when score>=60 then 1 else 0 end) / count(sno) from sc
group by cno order by 2 asc, 3 desc-- 15

16、查询不同老师所教不同课程平均分从高到低显示
select avg(score),cno from sc group by cno order by avg(score)desc;
select b.cno,c.tno,b.ww from course c join (select avg(score)ww,cno from sc group by cno order by avg(score)desc
)b on c.cno=b.cno;-- 16显示老师编号
select t.tname,p.tno,p.cno,p.ww from teacher t join (select b.cno,c.tno,b.ww from course c join
(select avg(score)ww,cno from sc group by cno order by avg(score)desc
)b on c.cno=b.cno)p on t.tno=p.tno;-- 16显示老师编号跟名字

17、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60]
select sc.cno 课程ID ,course.cname 课程名称,
sum(case when sc.score between 85 and 100 then 1 else 0 end)"[100-85]",
sum(case when sc.score >=70 and sc.score<85 then 1 else 0 end)"[70-85]",
sum(case when sc.score >=60 and sc.score<70 then 1 else 0 end)"[60-70]",
sum(case when sc.score <60 then 1 else 0 end)"[<60]"
from sc,course
where sc.cno=course.cno -- 特别的题
group by sc.cno,course.cname;-- 17
18、查询各科成绩前三名的记录:(不考虑成绩并列情况)
select sc.*,row_number()over(partition by cno order by score desc)t
from sc
select * from (select sc.*,row_number()over(partition by cno order by score desc)t
from sc)b where b.t<4-- 18

19、查询每门课程被选修的学生数
select count(*)学生数,cno from sc group by cno;
select c.cno,b.学生数 from course c full join (select count(*)学生数,cno from sc group by cno)b
on c.cno=b.cno;-- 19

20、查询出只选修了一门课程的全部学生的学号和姓名
select count(cno)mm,sno from sc group by sno having count(cno) = 1;
select b.sno,a.sname from student a join (select count(cno)mm,sno from sc group by sno having count(cno) = 1)b
on a.sno=b.sno;-- 20

21、查询男生、女生人数 select * from student;-- 学生学号学生姓名学生年龄学生性别
select count(ssex),ssex from student group by ssex; -- 21 select * from teacher;-- 老师编号老师姓名
select * from course;-- 课程号课程名字老师编号
select * from sc;-- 学号课程号成绩
22、查询姓“张”的学生名单
select * from student where sname like '张%';-- 22

23、查询同名同性学生名单，并统计同名人数
select count(*),sname from student group by sname;-- 同名

select count(*),ssex from student group by ssex;-- 同性
select sname,ssex,count (*) from student group by sname,ssex having count(*)=1;
select sname,ssex,count (*) from student group by sname,ssex having count(*)>1;-- 23

24、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列
select avg(score)t,cno from sc group by cno order by t,cno desc;-- 24

25、查询平均成绩大于85 的所有学生的学号、姓名和平均成绩
select avg(score),sno from sc group by sno having avg(score)>85
select s.sname,b.sno,b.aa from student s join (select avg(score)aa,sno from sc group by sno having avg(score)>85
)b on s.sno=b.sno;-- 25

26、查询课程名称为“数据库”，且分数低于60 的学生姓名和分数
select cno from course where cname = 'Oracle'
select sno,score from sc where score <60 and cno in (select cno from course where cname = 'Oracle'
)
select s.sname,b.score from student s join (select sno,score from sc where score <60 and cno in (select cno from course where cname = 'Oracle'
))b on s.sno=b.sno;-- 26

27、查询所有学生的选课情况；
select sno from sc group by sno
select b.cno,n.sno from sc b join (select sno from sc group by sno
)n on b.sno=n.sno-- 27
select t.sname,k.cno,k.sno from student t join (select b.cno,n.sno from sc b join (select sno from sc group by sno
)n on b.sno=n.sno)k on t.sno=k.sno;-- 27带姓名版

28、查询任何一门课程成绩在70 分以上的姓名、课程名称和分数；
select * from sc where score >=70
select * from student s join (select * from sc where score >=70
)b on s.sno=b.sno
select k.sname,c.cname,k.score from course c join (select * from student s join (select * from sc where score >=70
)b on s.sno=b.sno)k on c.cno=k.cno;-- 28

29、查询不及格的课程，并按课程号从大到小排列
select cno,score from sc where score <60 order by cno desc;-- 29

30、查询课程编号为c001 且课程成绩在80 分以上的学生的学号和姓名；
select * from sc where cno='c001' and score>80
select t.sname,b.sno,b.score from student t join (select * from sc where cno='c001' and score>80
)b on t.sno=b.sno;

31、求选了课程的学生人数
select distinct sno from sc-- 选了课的学生
select count (*) from (select distinct sno from sc );-- 31

32、查询选修“谌燕”老师所授课程的学生中，成绩最高的学生姓名及其成绩
select tno from teacher where tname = '谌燕';-- t002 燕子的教师编号
select cno from course where tno in (select tno from teacher where tname = '谌燕');-- 通过教师编号找到燕子教的全部课程编号
select * from sc where cno in (select cno from course where tno in (select tno from teacher where tname = '谌燕'))
-- 在sc表中找到燕子交的课程编号下与之相应的学生的编号跟成绩
select b.sno,b.score from (select * from sc where cno in (select cno from course where tno in (select tno from teacher where tname = '谌燕'))
)b where b.score in (select max(score) from (select * from sc where cno in
(select cno from course where tno in (select tno from teacher where tname = '谌燕'))
))-- 在以上所有的学生编号跟成绩中找到成绩最高的学生编号跟成绩
select t.sname,p.score from student t join (select b.sno,b.score from (select * from sc where cno in
(select cno from course where tno in (select tno from teacher where tname = '谌燕'))
)b where b.score in (select max(score) from (select * from sc where cno in -- 32
(select cno from course where tno in (select tno from teacher where tname = '谌燕'))
)))p on p.sno=t.sno-- 32
-- 最后跟student表中的编号相连接显现出名字跟成绩结束妈的真多

33、查询各个课程及相应的选修人数
select count(*)选课人数,cno from sc group by cno;
select c.cno,b.选课人数 from course c full join (select count(*)选课人数,cno from sc group by cno
)b on c.cno=b.cno -- 33

34、查询不同课程成绩相同的学生的学号、课程号、学生成绩
select count(*),score from sc group by score having count(*)>1;-- 成绩相同的学生成绩数量
select * from sc where score in (select score from sc group by score having count(*)>1);-- 34

35、查询每门功课成绩最好的前两名
select * from sc where cno = 'c001'
select distinct cno from sc
select * from sc where cno = 'c001' order by score desc
select s.*,row_number()over(partition by cno order by score desc) r from sc s;
select s.*,row_number()over(partition by cno order by score desc) r from sc s

select * from (select s.*,row_number()over(partition by cno order by score desc) r from sc s)b
where r <3-- 35

36、统计每门课程的学生选修人数（超过10 人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，若人数相同，按课程号升序排列
select cno,count (*) from sc group by cno order by count(*) desc,cno asc having count(*)>10
select * from (select cno,count (*)h from sc group by cno order by count(*) desc,cno asc)b
where b.h>10-- 36

37、检索至少选修两门课程的学生学号
select count(*) r ,sno from sc group by sno having count(*) >=2-- 37
38、查询全部学生都选修的课程的课程号和课程名
select s.cno,c.cname from (select cno from sc group by cno )s join course c on s.cno=c.cno -- 38

select * from student;-- 学生学号学生姓名学生年龄学生性别
select * from teacher;-- 老师编号老师姓名
select * from course;-- 课程号课程名称老师编号
select * from sc;-- 学号课程号成绩
39、查询没学过“谌燕”老师讲授的任一门课程的学生姓名
select tno from teacher where tname='谌燕';
select cno from course where tno in (select tno from teacher where tname='谌燕')
select sno from sc where cno not in (select cno from course where tno in (select tno from teacher where tname='谌燕'))

select t.sname from student t full join sc s on t.sno=s.sno where cno in
(select cno from course where tno in (select tno from teacher where tname='谌燕'))
-- 学过燕子课程的人名，已经跟student 连接起来了

select t.sname from student t full join sc s on t.sno=s.sno where t.sname not in
(select t.sname from student t full join sc s on t.sno=s.sno where cno in
(select cno from course where tno in (select tno from teacher where tname='谌燕')))-- 39

40、查询两门以上不及格课程的同学的学号及其平均成绩||\\
select * from sc where score < 60
select s.*,rownum r from
select b.score,b.sno from (select * from sc where score < 60)b group by score,sno having count (*)>2
select avg(k.score)h from (select b.score,b.sno from (select * from sc where score < 60)b group by score,sno having count (*)>2
) k
select * from (select b.score,b.sno from (select * from sc where score < 60)b group by score,sno having count (*)>2
)a full join (select avg(k.score)h from (select b.score,b.sno from (select * from sc where score < 60)b group by score,sno having count (*)>2
) k )b on a.sno = b.h-- 40
41、检索“c004”课程分数小于60，按分数降序排列的同学学号
select * from sc where cno ='c004' and score <60 order by score desc;-- 41

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