经典50道SQL练习题

前言

作为一个SQL小白,在一个月的努力后终于把这50道练习题做完了,分享一下我的答案给大家,说不定能给你提供一些思路。

我使用的是在线SQL,个人认为十分方便,使用的版本是“Ms SQL Server 2017”。

一、数据表

  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
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');
  1. 课程表 Course(CId,Cname,TId) – CId 课程编号,Cname 课程名称,TId 教师编号
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');
  1. 教师表 Teacher(TId,Tname)–TId 教师编号,Tname 教师姓名
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');
  1. 成绩表 SC(SId,CId,score)–SId 学生编号,CId 课程编号,score 分数
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);

二、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
    1.1 查询同时存在” 01 “课程和” 02 “课程的情况
    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 )
    1.3 查询不存在” 01 “课程但存在” 02 "课程的情况
  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
  3. 查询在 SC 表存在成绩的学生信息
  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 )
    4.1 查有成绩的学生信息
  5. 查询「李」姓老师的数量
  6. 查询学过「张三」老师授课的同学的信息
  7. 查询没有学全所有课程的同学的信息
  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
  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
  10. 查询没学过"张三"老师讲授的任一门课程的学生姓名
  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
  12. 检索" 01 "课程分数小于 60,按分数降序排列的学生信息
  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
  14. 查询各科成绩最高分、最低分和平均分
  15. 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
  16. 按各科成绩进行排序,并显示排名, Score 重复时保留名次空缺
  17. 按各科成绩进行排序,并显示排名, Score 重复时合并名次
  18. 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
  19. 查询学生的总成绩,并进行排名,总分重复时保留名次空缺
  20. 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
  21. 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
  22. 查询各科成绩前三名的记录
  23. 查询每门课程被选修的学生数
  24. 查询出只选修两门课程的学生学号和姓名
  25. 查询男生、女生人数
  26. 查询名字中含有「风」字的学生信息
  27. 查询同名同性学生名单,并统计同名人数
  28. 查询 1990 年出生的学生名单
  29. 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
  30. 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
  31. 查询课程名称为「数学」,且分数低于 60 的学生姓名和分数
  32. 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)
  33. 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
  34. 查询不及格的课程
  35. 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
  36. 求每门课程的学生人数
  37. 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
  38. 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
  39. 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
  40. 查询每门功成绩最好的前两名
  41. 统计每门课程的学生选修人数(超过 5 人的课程才统计)。
  42. 检索至少选修两门课程的学生学号
  43. 查询选修了全部课程的学生信息
  44. 查询各学生的年龄,只按年份来算
  45. 按照出生日期来算,当前月日 < 出生年月的月日则,年龄减一
  46. 查询本周过生日的学生
  47. 查询下周过生日的学生
  48. 查询本月过生日的学生
  49. 查询下月过生日的学生

三、题解

  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 t1.sid, t1.score as class1,t2.score as class2 from
(select sid,cid,score from sc where cid = '01') t1,
(select sid,cid,score from sc where cid = '02') t2
where t1.sid = t2.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 sc.sid from sc
Where sc.cid = '01' and sc.sid in (select sid from sc where cid = '02')
  • 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 sc.cid =01) t1
Left join (select * from sc where sc.cid =02) t2
On t1.sid = t2.sid
  • 1.3 查询不存在" 01 “课程但存在” 02 "课程的情况
Select * from sc
Where sc.cid =02and sc.sid not in (select sid from sc where cid =01)
  1. 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 sc.sid, st.sname, avg(sc.score) avg_score from sc
Join student st
On sc.sid = st.sid
Group by sc.sid
Having avg_score >= 60
  1. 查询在 SC 表存在成绩的学生信息
Select sc.*, st.* from sc
Left join student st
On sc.sid = st.sid
  1. 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 st.sid, st.sname, count(sc.cid), sum(sc.score) from student st
Left join sc 
On st.sid = sc.sid
Group by st.sid
  • 4.1 查有成绩的学生信息
Select st.* from student t
Where st.sid in (select sid from sc)
  1. 查询「李」姓老师的数量
Select count(tid) from teacher
Where tname like’李%
  1. 查询学过「张三」老师授课的同学的信息
Select sc.sid, st.* from sc
Left join student st
On sc.sid = st.sid
Where sc.cid in (Select c.cid from course c
Join teacher t
On c.tid = t.tid
Where t.tname = ‘张三’)
  1. 查询没有学全所有课程的同学的信息
Select st.* from student t
Where st.sid not in 
(select sid from sc group by sid having count(cid) = (select count(cid) from course))
  1. 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 sc.sid, st.* from sc
Join student st
On sc.sid = st.sid
Where sc.cid in (Select cid from sc where sid =01)
  1. 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 sc.sid, st.* from sc
Join student st
On sc.sid = st.sid
where sc.cid in (Select cid from sc where sid = '01') and sc.sid != '01'
group by sc.sid
having count(sc.cid) = (Select count(cid) from sc where sid = '01')
  1. 查询没学过"张三"老师讲授的任一门课程的学生姓名
select st.sname from student st
where st.sname not in 
(select st.sname from student st,sc,course c,teacher t
where st.sid = sc.sid and sc.cid = c.cid and c.tid = t.tid and t.tname = '张三')
  1. 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 sc.sid,st.sname,avg(sc.score) from sc
join student st
on sc.sid = st.sid
group by sc.sid
having sum(case when sc.score < 60 then 1 else 0 end)>=2
  1. 检索" 01 "课程分数小于 60,按分数降序排列的学生信息
select sc.sid,st.sname from sc
join student st
on sc.sid = st.sid
where sc.cid = '01' and sc.score <60
order by sc.score desc
  1. 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 sid,avg(score) over(partition by sid) as avg_score,cid,score from sc
order by avg_score desc
select sc.sid,t1.avg_score,sc.cid,sc.score from sc
left join (select sid,avg(score) as avg_score,cid,score from sc group by sid) t1
on sc.sid = t1.sid
order by 2 desc
  1. 查询各科成绩最高分、最低分和平均分:
select cid,max(score),avg(score) from sc
group by cid
  1. 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
select sc.cid,c.cname,max(sc.score),min(sc.score),avg(sc.score),
sum(case when sc.score>=60 then 1 else 0 end)*1.0/count(sc.score) 及格,
sum(case when sc.score between 70 and 80 then 1 else 0 end)*1.0/count(sc.score) 中等,
sum(case when sc.score between 80 and 90 then 1 else 0 end)*1.0/count(sc.score) 优良,
sum(case when sc.score>=90 then 1 else 0 end)*1.0/count(sc.score) 优秀
from sc
join course c
on sc.cid = c.cid
group by sc.cid
  1. 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 cid, rank() over (partition by cid order by score desc) rank,score from sc
  1. 按各科成绩进行排序,并显示排名, Score 重复时合并名次
select cid, dense_rank() over (partition by cid order by score desc) rank,score from sc
  1. 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 cid, count(sid) from sc
group by cid
order by 2 desc,1
  1. 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 sum(score) sum_score, rank() over (order by sum(score) desc) rank from sc
group by sid
  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

  2. 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 cid,
sum(case when score between 85 and 100 then 1 else 0 end)*1.0/count(sid) '85-100',
sum(case when score between 70 and 85 then 1 else 0 end)*1.0/count(sid) '70-85',
sum(case when score between 60 and 70 then 1 else 0 end)*1.0/count(sid) '60-70',
sum(case when score between 85 and 100 then 1 else 0 end)*1.0/count(sid) '0-60'
from sc group by cid
  1. 查询各科成绩前三名的记录
select * from (select cid, sid,score, row_number() over (partition by cid order by score desc) as rank from sc) t
where t.rank <= 3
  1. 查询每门课程被选修的学生数
select cid, count(sid) from sc
group by cid
  1. 查询出只选修两门课程的学生学号和姓名
select sc.sid from sc
group by sid
having count(distinct cid)=2
  1. 查询男生、女生人数
select count(distinct t1.sid),count(distinct t2.sid)from 
(select sid from student where ssex = '男') t1,
(select sid from student where ssex = '女') t2
  1. 查询名字中含有「风」字的学生信息
select * from student
where sname like '%风%'
  1. 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;
select * from
(select t1.* from student t1, student t2
where t1.sname = t2.sname and t1.sid != t2.sid group by t1.sid) a
  1. 查询 1990 年出生的学生名单
select * from student
where sage between '1990-01-01' and '1991-01-01'
  1. 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 distinct cid, avg(score) over (partition by cid) avg_score from sc
order by 2 desc,1
  1. 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 * from
(select distinct sid , avg(score) over (partition by sid) avg_score from sc) t1
where avg_score >= 85
  1. 查询课程名称为「数学」,且分数低于 60 的学生姓名和分数
select st.sname,sc.*,c.cname from sc
join course c
on sc.cid = c.cid and c.cname = '数学'
join student st
on sc.sid = st.sid
where sc.score < 60
  1. 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 st.sid, st.sname,sc.* from student st
left join sc
on st.sid = sc.sid
  1. 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 sc.sid, st.sname, c.cname, sc.score from sc
join  student st
on sc.sid = st.sid
join course c
on sc.cid = c.cid
where sc.score > 70
  1. 查询不及格的课程
select sc.sid, st.sname, c.cname, sc.score from sc
join  student st
on sc.sid = st.sid
join course c
on sc.cid = c.cid
where sc.score < 60
  1. 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 sc.cid, sc.sid, st.sname,sc.score from sc
join student st
on sc.sid = st.sid 
where sc.cid = '01' and sc.score >=80
  1. 求每门课程的学生人数
select sc.cid, count(sc.sid) from sc
group by sc.cid
  1. 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 st.*,max(sc.score) from sc
join course c 
on sc.cid = c.cid
join teacher t
on c.tid = t.tid and t.tname = '张三'
join student st
on sc.sid = st.sid
  1. 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 t1.* from
(select st.*, sc.score from sc
join course c 
on sc.cid = c.cid
join teacher t
on c.tid = t.tid and t.tname = '张三'
join student st
on sc.sid = st.sid) t1,
(select st.*,max(sc.score) as max_score from sc
join course c 
on sc.cid = c.cid
join teacher t
on c.tid = t.tid and t.tname = '张三'
join student st
on sc.sid = st.sid) t2
where t1.score = t2.max_score
  1. 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,
(select sid,cid,score from sc
group by sid
having count(distinct cid) > count(distinct score)) t1
where sc.sid = t1.sid
  1. 查询每门功成绩最好的前两名
select * from 
(select cid, sid, row_number() over (partition by cid order by score desc) as rank from sc)
 t1
where rank<=2
  1. 统计每门课程的学生选修人数(超过 5 人的课程才统计)。
select * from 
(select cid, count(distinct sid) as num from sc 
group by cid) t1
where num > 5
  1. 检索至少选修两门课程的学生学号
select sid from 
(select sid, count(cid) as num from sc group by sid) t1
where num > 2
  1. 查询选修了全部课程的学生信息
select sid from sc
group by sid
having count(distinct cid) = (select count(distinct cid) from course)
  1. 查询各学生的年龄,只按年份来算
select sid, sname, timestampdiff(year, sage, current_date()) age from student
  1. 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, sage, current_date()) age from student
  1. 查询本周过生日的学生
select *
from student 
where WEEKOFYEAR(student.Sage)=WEEKOFYEAR(current_date())
  1. 查询下周过生日的学生
select *
from student 
where WEEKOFYEAR(student.Sage)=WEEKOFYEAR(current_date())+1
  1. 查询本月过生日的学生
select *
from student 
where MONTH(student.Sage)=MONTH(current_date())
  1. 查询下月过生日的学生
select *
from student 
where MONTH(student.Sage)=MONTH(current_date())+1

你可能感兴趣的:(sql)