经典sql题

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@will

发布于 2022-11-19 15:40:02

7670

发布于 2022-11-19 15:40:02

文章被收录于专栏：一些小记录

前言

最近在重新看数据库的相关知识，发现对sql的编写忘的差比多了，50道经典SQL题是网上广为流传的SQL题，很多人用它作为SQL入门学习，所以找来做做。题目来源于网上。

数据库

数据库创建：

create table Student(SId varchar(10),Sname varchar(10),Sage datetime,Ssex varchar(10));
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' , '1990-05-20' , '男');
insert into Student values('04' , '李云' , '1990-08-06' , '男');
insert into Student values('05' , '周梅' , '1991-12-01' , '女');
insert into Student values('06' , '吴兰' , '1992-03-01' , '女');
insert into Student values('07' , '郑竹' , '1989-07-01' , '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' , '2017-12-30' , '女');
insert into Student values('12' , '赵六' , '2017-01-01' , '女');
insert into Student values('13' , '孙七' , '2018-01-01' , '女');

create table Course(CId varchar(10),Cname nvarchar(10),TId varchar(10));
insert into Course values('01' , '语文' , '02');
insert into Course values('02' , '数学' , '01');
insert into Course values('03' , '英语' , '03');

create table Teacher(TId varchar(10),Tname varchar(10));
insert into Teacher values('01' , '张三');
insert into Teacher values('02' , '李四');
insert into Teacher values('03' , '王五');

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

1. 查询" 01 "课程比" 02 "课程成绩高的学生的信息及课程分数

#思路：找出01和02课程的成绩表，再进行比较
select a.*,t1.score 01_成绩,t2.score 02_成绩
from student a, 
  (select * from sc where cid='01') t1,
  (select * from sc where cid='02') t2
where a.sid=t1.sid and t1.score>t2.score;

1.1 查询同时存在" 01 "课程和" 02 "课程的情况

select a.*,t1.score 01_成绩,t2.score 02_成绩
from student a, 
  (select * from sc where cid='01') t1,
  (select * from sc where cid='02') t2
where a.sid=t1.sid and t1.sid=t2.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 a.*,t1.score 01_成绩,t2.score 02_成绩
from student a, (select * from sc where cid='01') t1 left join 
  (select * from sc where cid='02') t2 on t1.sid=t2.sid
where a.sid=t1.sid;

1.3 查询不存在" 01 "课程但存在" 02 "课程的情况

select a.*,sc.score 02_成绩
from student a, sc
where a.sid=sc.sid and sc.cid='02' and
    sc.sid not in (select sid from sc where cid='01');

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 a.sid,a.sname,avg(b.score)
from student a, sc b
where a.sid=b.sid
group by sid
having avg(score)>=60;

3. 查询在 SC 表存在成绩的学生信息

select a.*
from student a, sc b
where a.sid=b.sid
group by b.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 a.sid,a.sname,count(sc.score),sum(sc.score)
from student a left join sc on a.sid=sc.sid
group by a.sid;

4.1 查有成绩的学生信息

select a.* from student a
where a.sid in (select sid from sc);

5. 查询「李」姓老师的数量

select count(tid)
from teacher t
where tname like '李%';

6. 查询学过「张三」老师授课的同学的信息

select a.*
from student a, sc b, course c, teacher d
where a.sid=b.sid and b.cid=c.cid and c.tid=d.tid and d.tname='张三';

7. 查询没有学全所有课程的同学的信息

select a.*
from student a left join sc on a.sid=sc.sid
group by a.sid
having count(a.sid)< (select count(cid) 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 distinct a.*
from student a,sc b
where a.sid=b.sid and (b.cid in (select cid from sc where sid='01'))

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（略复杂）

select a.*
from student a,sc b
where a.sid=b.sid and 
  b.cid in (select cid from sc where sid='01') and a.sid!='01'
group by a.sid
having count(b.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 distinct student.sname
from student
where student.sname not in 
  (select a.sname from student a,sc b,course c,teacher d
   where a.sid=b.sid and b.cid=c.cid 
      and c.tid= d.tid and d.tname='张三');

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 student.sid, student.sname, avg(score)
from student,sc
where student.sid=sc.sid and sc.score<60
group by student.sid
having count(*)>=2

12. 检索" 01 "课程分数小于 60，按分数降序排列的学生信息

select student.*,sc.score
from student,sc
where student.sid=sc.sid and sc.cid='01'and sc.score<60
order by 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

#合理利用左连接右连接特点
select sc.sid,a.avg_score,sc.cid,sc.score 
from sc left join 
    (select sid,avg(score) avg_score,cid,score from sc group by sid) a
    on sc.sid = a.sid
order by a.avg_score desc

14. 查询各科成绩最高分、最低分和平均分：

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，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 sc.cid, cname, count(*) 选修人数,max(score) 最高分,min(score) 最低分,avg(score) 平均分,
  sum(case when score>=60 then 1 else 0 end)/count(*) 及格率,
  sum(case when score>=70 and score<80 then 1 else 0 end)/count(*) 中等率,
  sum(case when score>=80 and score<90 then 1 else 0 end)/count(*) 优良率,
  sum(case when score>=90 then 1 else 0 end)/count(*) 优秀率
from sc,course
where sc.cid=course.cid
group by sc.cid
order by count(*) desc,sc.cid asc

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.*, count(a.score) as 排名
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, 排名 ASC;

15.1 按各科成绩进行排序，并显示排名， Score 重复时合并名次

select a.*, count(b.score)+1 as 排名
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, 排名 ASC;

16. 查询学生的总成绩，并进行排名，总分重复时保留名次空缺

#使用窗口函数rank进行排序
select sid,sum(score), rank() over(order by sum(score) desc) 排名
from sc
group by sid;

16.1 查询学生的总成绩，并进行排名，总分重复时不保留名次空缺

#窗口函数dense_rank
select sid,sum(score), dense_rank() over(order by sum(score) desc) 排名
from sc
group by sid;

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 sc.cid, cname, count(*) 选修人数,max(score) 最高分,min(score) 最低分,avg(score) 平均分,
  sum(case when score<60 then 1 else 0 end) '0-60',
  sum(case when score>=60 and score<70 then 1 else 0 end) '60-70',
  sum(case when score>=70 and score<85 then 1 else 0 end) '70-85',
  sum(case when score>=85 then 1 else 0 end) '85-100'
from sc,course
where sc.cid=course.cid
group by sc.cid
order by count(*) desc,sc.cid asc;

18. 查询各科成绩前三名的记录

#对每个成绩进行排名后，选取前三名
select sic,cid,score
from (select sid,score, row_number() over(partition by cid order by score desc) 排名
      from sc) t1
where 排名 < 4;

19. 查询每门课程被选修的学生数

select cid, count(*) 选修人数
from sc
group by cid
order by 选修人数 desc;

20. 查询出只选修两门课程的学生学号和姓名

select student.sid, sname,count(*) 选修课程数量
from student, sc
where student.sid = sc.sid
group by sid
having 选修课程数量=2;

21. 查询男生、女生人数

select sum(case when ssex='女' then 1 else 0 end) 女生人数,
       sum(case when ssex='男' then 1 else 0 end) 男生人数
from student;

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 *,count(*) 同名人数
from student
group by sname, ssex;

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 course.cid,cname, avg(score)
from sc, course
where course.cid=sc.cid
group by cid
order by avg(score),sc.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 student.sid, sname, avg(score)
from student,sc
where student.sid=sc.sid
group by student.sid
having avg(score)>=85;

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 sname,score
from student,sc,course
where student.sid=sc.sid and sc.cid=course.cid
  and cname='数学' and 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 *
from student left join sc on student.sid=sc.cid;

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 sname,cname,score
from student,sc,course
where student.sid=sc.sid and sc.cid=course.cid
  and score > 70;

30. 查询不及格的课程

select sname,cname,score
from student,sc,course
where student.sid=sc.sid and sc.cid=course.cid
  and 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 student.sid,sname
from student,sc
where student.sid=sc.sid and cid='01' and score>80;

32. 求每门课程的学生人数

select sc.cid,cname,count(score) 选课人数
from sc, course
where sc.cid=course.cid
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 student.*, max(score)
from student,sc,course,teacher
where student.sid=sc.sid and sc.cid=course.cid
  and course.tid=teacher.tid and tname='张三';

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

select student.*, score
from student,sc,course,teacher,
  (select max(score) 最高分
   from student,sc,course,teacher
   where student.sid=sc.sid and sc.cid=course.cid
   and course.tid=teacher.tid and tname='张三') t1
where student.sid=sc.sid and sc.cid=course.cid
  and course.tid=teacher.tid and tname='张三'
  and score=t1.最高分

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 sc.* from sc
group by cid,score
having count(score)>1;

36. 查询每门功成绩最好的前两名

select student.*,rank() over(partition by cid order by sum(score) desc) 排名
from student,sc
where student.sid=sc.sid
having 排名<3;

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 course.*,count(score) 选修人数
from course,sc
where course.cid=sc.cid
group by sc.cid
having 选修人数>=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(distinct score)>=2;

39. 查询选修了全部课程的学生信息

select student.*
from student,sc
where student.sid=sc.sid
group by student.sid
having count(distinct score)=(select count(*) from course);

40. 查询各学生的年龄，只按年份来算

select sid,sname,ssex,year(current_date)-year(sage) 年龄
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

#时间差函数timestampdiff
select sid,sname,ssex,timestampdiff(year,sage,current_date()) 年龄
from student;

42. 查询本周过生日的学生

#将sage拆分
select *
from student
where week (date_format(NOW(), '%Y%m%d'),1) = 
    week(str_to_date(concat(date_format(NOW(), '%Y'),date_format(sage, '%m%d')),
			'%Y%m%d'),1);

43. 查询下周过生日的学生

select *
from student
where week (date_format(NOW(), '%Y%m%d'),1) = 
    week(str_to_date(concat(date_format(NOW(), '%Y'),date_format(sage, '%m%d')),
			'%Y%m%d'),1)+1;

44. 查询本月过生日的学生

select *
from student
where month(sage)=month(current_date());

45. 查询下月过生日的学生

select *
from student
where month(sage)=month(current_date())+1;

原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。

如有侵权，请联系 cloudcommunity@tencent.com 删除。

sql

原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。

如有侵权，请联系 cloudcommunity@tencent.com 删除。

sql

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