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sql练习题-第一版

由 落爺英雄遲暮 提交于 2020-01-17 23:59:25

前言: 网上现在有不少的sql题，最多的就是那50道sql题了。我自己也做了下，有意见的小伙伴可以随时发留言给我哈。

数据表介绍

-1.学生表
Student(SId,Sname,Sage,Ssex)
–SId 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别

–2.课程表
Course(CId,Cname,TId)
–CId 课程编号,Cname 课程名称,TId 教师编号

–3.教师表
Teacher(TId,Tname)
–TId 教师编号,Tname 教师姓名

–4.成绩表
SC(SId,CId,score)
–SId 学生编号,CId 课程编号,score 分数

创建语句

– 学生表

create table Student(SId varchar(10),Sname varchar(10),Sage datetime,Ssex varchar(10));

– 课程表

create table Course(CId varchar(10),Cname nvarchar(10),TId varchar(10));

– 老师表

create table Teacher(TId varchar(10),Tname varchar(10));

– 成绩表

create table SC(SId varchar(10),CId varchar(10),score decimal(18,1));

表数据

– 学生表数据

insert into Student values('01' , '赵雷' , '1990-01-01' , '男');
insert into Student values('02' , '钱电' , '1990-12-21' , '男');
insert into Student values('03' , '孙风' , '1990-12-20' , '男');
insert into Student values('04' , '李云' , '1990-12-06' , '男');
insert into Student values('05' , '周梅' , '1991-12-01' , '女');
insert into Student values('06' , '吴兰' , '1992-01-01' , '女');
insert into Student values('07' , '郑竹' , '1989-01-01' , '女');
insert into Student values('09' , '张三' , '2017-12-20' , '女');
insert into Student values('10' , '李四' , '2017-12-25' , '女');
insert into Student values('11' , '李四' , '2012-06-06' , '女');
insert into Student values('12' , '赵六' , '2013-06-13' , '女');
insert into Student values('13' , '孙七' , '2014-06-01' , '女');

– 课程表数据

insert into Course values('01' , '语文' , '02');
insert into Course values('02' , '数学' , '01');
insert into Course values('03' , '英语' , '03');

– 老师表数据

insert into Teacher values('01' , '张三');
insert into Teacher values('02' , '李四');
insert into Teacher values('03' , '王五');

– 成绩表数据

insert into SC values('01' , '01' , 80);
insert into SC values('01' , '02' , 90);
insert into SC values('01' , '03' , 99);
insert into SC values('02' , '01' , 70);
insert into SC values('02' , '02' , 60);
insert into SC values('02' , '03' , 80);
insert into SC values('03' , '01' , 80);
insert into SC values('03' , '02' , 80);
insert into SC values('03' , '03' , 80);
insert into SC values('04' , '01' , 50);
insert into SC values('04' , '02' , 30);
insert into SC values('04' , '03' , 20);
insert into SC values('05' , '01' , 76);
insert into SC values('05' , '02' , 87);
insert into SC values('06' , '01' , 31);
insert into SC values('06' , '03' , 34);
insert into SC values('07' , '02' , 89);
insert into SC values('07' , '03' , 98);

sql及答案

1.查询" 01 “课程比” 02 "课程成绩高的学生的信息及课程分数

select * from student s RIGHT JOIN (
select s1.SId,c1,c2 from (select SId,score as c1 from sc where CId=01) s1,(select SId,score as c2 from sc where CId=02) s2 
where s1.SId=s2.SId and s1.c1>s2.c2 ) e on e.SId= s.SId;

– 1.1 查询同时存在" 01 “课程和” 02 “课程的情况

select SId from sc where CId=01
select SId from sc where CId=02
select s1.SId from (select SId from sc where CId=01) s1,(select SId from sc where CId=02) s2 where s1.SId=s2.SId;

– 1.2 查询存在” 01 “课程但可能不存在” 02 “课程的情况(不存在时显示为 null )

select * from 
(select * from sc where CId=01) c1 
left join 
(select * from sc where CId=02) c2
on c1.SId=c2.SId;

– 1.3 查询不存在” 01 “课程但存在” 02 "课程的情况

select * from 
(select * from sc where CId<>01) c1 
left join 
(select * from sc where CId=02) c2
on c1.SId=c2.SId;

2.查询平均成绩大于等于 60 分的同学的学生编号和学生姓名和平均成绩

select s2.SId,s2.Sname,avg(s1.score) from sc s1 left join student s2 on s1.SId=s2.SId
group by s1.SId,s2.Sname having avg(s1.score)>60;

3.查询在 SC 表存在成绩的学生信息

select * from sc s1 left join student s2 on s1.SId=s2.SId;

4.查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩(没成绩的显示为 null )

select s1.SId 学生编号,s1.Sname 学生姓名,count(s2.CId) 选课总数,sum(s2.score) 总成绩 from student s1 
left join sc s2 on s1.SId=s2.SId group by s1.SId,s1.Sname;

5.查询「李」姓老师的数量

select count(*) from teacher where Tname like '李%';

6.查询学过「张三」老师授课的同学的信息

select s1.SId,s1.Sname,s1.Sage,s1.Ssex,s2.CId,s2.score,c1.Cname from student s1,sc s2,course c1,teacher t1
where s1.SId=s2.SId and s2.CId=c1.CId and c1.TId=t1.TId and t1.Tname='张三';

7.查询没有学全所有课程的同学的信息

select * from student where SId in (select SId from sc group by SId having count(CId)<(select count(*) from course));

– 8.查询至少有一门课与学号为" 01 “的同学所学相同的同学的信息

select s1.SId,s1.Sname from student s1,sc s2 where EXISTS (select CId from sc where SId=01) 
and s1.SId=s2.SId group by s1.SId,s1.Sname;

9.查询和” 01 “号的同学学习的课程 完全相同的其他同学的信息

select * from student where 
SId in (select SId from sc group by SId having count(CId) = (select count(CId) from sc where SId=01) );

10.查询没学过"张三"老师讲授的任一门课程的学生姓名

select s1.SId,s1.Sname from student s1,sc s2,course c1,teacher t1 where s1.SId=s2.SId and s2.CId=c1.CId and c1.TId=t1.TId
and t1.Tname <> '张三' group by s1.SId,s1.Sname;

11.查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩

select s2.*,score from (select SId,avg(score) as score from sc where score<60 group by SId having count(SId)>=2) s1
left join student s2 on s1.SId=s2.SId;

12.检索” 01 "课程分数小于 60，按分数降序排列的学生信息

select * from student s1 left join sc s2 on s1.SId=s2.SId
where s2.CId=01 and s2.score<60 order by s2.score desc;

13.按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩 –

select a.*,
sum(case when b.CId=01 then b.score else 0 end) as s01,
sum(case when b.CId=02 then b.score else 0 end) as s02,
sum(case when b.CId=03 then b.score else 0 end) as s03,
avg(case when b.score is null then 0 else b.score end) as savg
from student a left join sc b on a.SId=b.SId group by 1,2,3,4 order by savg desc;

14.查询各科成绩最高分、最低分和平均分：

select max(score) 最高分,min(score) 最低分,avg(score) 平均分,CId from sc group by CId

以如下形式显示：课程 ID，课程 name，最高分，最低分，平均分，及格率，中等率，优良率，优秀率 –
及格为>=60，中等为：70-80，优良为：80-90，优秀为：>=90
要求输出课程号和选修人数

select 
a.cid as 课程ID,
a.cname as 课程name, 
count(SId) 选修人数,
max(b.score) as 最高分,
min(b.score) as 最低分,
avg(b.score) as 平均分,
SUM(CASE WHEN b.score>=60 THEN 1 ELSE 0 END)/COUNT(1) as 及格率,
SUM(CASE WHEN b.score>=70 AND b.score<80 THEN 1 ELSE 0 END)/COUNT(1) as 中等率,
SUM(CASE WHEN b.score>=80 AND b.score<90 THEN 1 ELSE 0 END)/COUNT(1) as 优良率,
SUM(CASE WHEN b.score>=90 THEN 1 ELSE 0 END)/COUNT(1) as 优秀率
FROM Course a
INNER JOIN SC b
ON a.cid=b.cid
GROUP BY 1,2 ;

15.按各科成绩进行排序，并显示排名， Score 重复时保留名次空缺

select a.cid, a.sid, a.score, count(b.score)+1 as v
from sc as a
left join sc as b
on a.score<b.score and a.cid = b.cid
group by a.cid, a.sid,a.score
order by a.cid, v ASC;

查询学生的总成绩，并进行排名，总分重复时保留名次空缺 –

select a.cid, a.sid, a.score, sum(b.score) , count(b.score)+1 as v from sc a 
left join sc b on a.score<b.score and a.CId=b.CId
group by a.cid, a.sid,a.score order by a.cid, v ASC;

17.统计各科成绩各分数段人数：课程编号，课程名称，[100-85]，[85-70]，[70-60]，[60-0] 及所占百分比

select 
b.cid as 课程ID,
b.cname as 课程name, 
SUM(CASE WHEN a.score<=100 AND a.score>80 THEN 1 ELSE 0 END) as s1,
SUM(CASE WHEN a.score<=85 AND a.score>70 THEN 1 ELSE 0 END) as s2,
SUM(CASE WHEN a.score<=70 AND a.score>60 THEN 1 ELSE 0 END) as s3,
SUM(CASE WHEN a.score<=70 AND a.score>0 THEN 1 ELSE 0 END) as s4
FROM SC a
left JOIN Course b
ON a.cid=b.cid
GROUP BY 1,2;

18.查询各科成绩前三名的记录

select  from 
(select SId,CId,score from sc where CId=01 order by score desc limit 0,3) as s1,
(select SId,CId,score from sc where CId=02 order by score desc limit 0,3) as s2,
(select SId,CId,score from sc where CId=03 order by score desc limit 0,3) as s3
where s1.SId=s2.SId and s2.SId=s3.SId 

select * from sc as s1 where (select count(*) from sc as s2 where s1.CId=s2.CId and s1.score<s2.score ) <3
order by cid asc, s1.score desc;

19.查询每门课程被选修的学生数

select CId,count(SId) from sc group by CId;

20.查询出只选修两门课程的学生学号和姓名
select s1.SId,s1.Sname from  student as s1 inner join (select SId from sc group by SId having count(CId)=2) as s2
on s1.SId=s2.SId;

21.查询男生、女生人数

select Ssex, count(SId) from student where Ssex='男' 
union
select Ssex, count(SId) from student where Ssex='女';

select Ssex, count(*) from student group by Ssex;

22.查询名字中含有「风」字的学生信息

select * from student where Sname like '%风';

23.查询同名同性学生名单，并统计同名人数

select Sname,count(*) from student group by Sname having count(*)>1;

24.查询 1990 年出生的学生名单

select * from student where year(Sage) ='1990';

25.查询每门课程的平均成绩，结果按平均成绩降序排列，平均成绩相同时，按课程编号升序排列

select CId,avg(score) from sc group by CId order by avg(score) desc,cid asc;

26.查询平均成绩大于等于 85 的所有学生的学号、姓名和平均成绩

select s2.*,s1.avgscore from (select avg(score) as avgscore,SId from sc group by SId having avg(score)>85 ) as s1 inner join student s2
on s1.SId=s2.SId;

27.查询课程名称为「数学」，且分数低于 60 的学生姓名和分数

select s1.SId,s1.CId,s1.score,s2.Cname from sc as s1 inner join (select CId,Cname from course where Cname='数学') as s2
on s1.CId=s2.CId where s1.score<60;

28.查询所有学生的课程及分数情况（存在学生没成绩，没选课的情况）

select s1.SId,s1.Sname,s1.Sage,s1.Ssex,c1.CId,c1.Cname,s2.score from student s1 
left join sc s2 on s1.SId=s2.SId left join course c1 on s2.CId=c1.CId order by SId;

29.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 s1.SId,s2.Sname,c1.Cname,s1.score from sc s1 left join student s2 on s1.SId=s2.SId
left join course c1 on c1.CId=s1.CId where s1.score > 70 order by SId;

30.查询不及格的课程

select s1.SId,s1.CId,s1.score,c1.Cname from sc s1 left join course c1 on s1.CId=c1.CId 
where s1.score<60 ;

31.查询课程编号为 01 且课程成绩在 80 分以上的学生的学号和姓名

select s1.SId,s1.Sname,s1.Sage,s1.Ssex,s2.CId,s2.score from student s1 left join sc s2 on s1.SId=s2.SId 
where s2.CId=01 and s2.score>=80;

32.求每门课程的学生人数

select CId,count(SId) from sc group by CId;

33.成绩不重复，查询选修「张三」老师所授课程的学生中，成绩最高的学生信息及其成绩 –

select s1.SId,s1.Sname,s1.Sage,s1.Ssex,s2.CId,s2.score,c1.Cname,t1.Tname from student as s1,sc as s2,course as c1,teacher as t1 
where s1.SId=s2.SId and s2.CId=c1.CId and c1.TId=t1.TId
and t1.Tname='张三' order by s2.score desc limit 0,1

34.成绩有重复的情况下，查询选修「张三」老师所授课程的学生中，成绩最高的学生信息及其成绩

UPDATE sc SET score=90
where sid = "07"
and cid ="02";

select student.*, sc.score, sc.cid from student, teacher, course,sc 
where teacher.tid = course.tid
and sc.sid = student.sid
and sc.cid = course.cid
and teacher.tname = "张三"
and sc.score = (
    select Max(sc.score) 
    from sc,student, teacher, course
    where teacher.tid = course.tid
    and sc.sid = student.sid
    and sc.cid = course.cid
    and teacher.tname = "张三"
);

35.查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩

select s1.SId,s1.Sname,s2.CId,s2.score from student s1 inner join sc s2
on s1.SId=s2.SId where s2.score in (select score from sc group by score having count(*)>1);

36.查询每门功成绩最好的前两名

select a.sid,a.cid,a.score from sc as a 
left join sc as b 
on a.cid = b.cid and a.score<b.score
group by a.cid, a.sid,a.score
having count(b.cid)<2
order by a.cid;

37.统计每门课程的学生选修人数（超过 5 人的课程才统计）。

select CId,count(*) from sc group by CId having count(*)>5;

38.检索至少选修两门课程的学生学号

select SId from sc group by SId having count(CId)>=2;

39.查询选修了全部课程的学生信息

select s1.* from student s1 inner join (select SId from sc group by SId having count(CId)>2) s2 on s1.SId=s2.SId;

40.查询各学生的年龄，只按年份来算

select SId,Sname,TIMESTAMPDIFF(YEAR,student.Sage,CURDATE()) Sage,Ssex from student

41.按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一

select SId,Sname,TIMESTAMPDIFF(YEAR,student.Sage,CURDATE()) Sage,Ssex from student

42.查询本周过生日的学生

select *
from student 
where WEEKOFYEAR(student.Sage)=WEEKOFYEAR(CURDATE());

43.查询下周过生日的学生

select *
from student 
where WEEKOFYEAR(student.Sage)=WEEKOFYEAR(CURDATE())+1;

44.查询本月过生日的学生

select *
from student 
where MONTH(student.Sage)=MONTH(CURDATE());

45.查询下月过生日的学生

select *
from student 
where MONTH(student.Sage)=MONTH(CURDATE())+1;
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