经典50道SQL练习题
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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');
2.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');
3.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');
4.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
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 = ‘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
(使用一些聚合函数必需先分组)
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
3、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
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 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)
5、查询「李」姓老师的数量
Select count(tid) from teacher
Where tname like’李%’
6、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’)
7、查询没有学全所有课程的同学的信息
Select st.* from student st
Where st.sid not in
(select sid from sc group by sid having count(cid) = (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 sc.sid, st.* from sc
Join student st
On sc.sid = st.sid
Where sc.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
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')
10、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')
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 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
12、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
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 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
14、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
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
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
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
select cid, rank() over (partition by cid order by score desc) rank,score from sc
17、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
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
select cid, count(sid) from sc
group by cid
order by 2 desc,1
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
select sum(score) sum_score, rank() over (order by sum(score) desc) rank from sc
group by sid
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
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
22、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
23、查询每门课程被选修的学生数
select cid, count(sid) from sc
group by cid
24、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
25、查询男生、女生人数
select count(distinct t1.sid) 男,count(distinct t2.sid) 女 from
(select sid from student where ssex = '男') t1,
(select sid from student where ssex = '女') t2
26、查询名字中含有「风」字的学生信息
select * from student
where sname like '%风%'
27、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
28、查询 1990 年出生的学生名单
select * from student
where sage between '1990-01-01' and '1991-01-01'
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
select distinct cid, avg(score) over (partition by cid) avg_score from sc
order by 2 desc,1
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
select * from
(select distinct sid , avg(score) over (partition by sid) avg_score from sc) t1
where avg_score >= 85
31、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
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）
select st.sid, st.sname,sc.* from student st
left join sc
on st.sid = sc.sid
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
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
34、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
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
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
36、求每门课程的学生人数
select sc.cid, count(sc.sid) from sc
group by sc.cid
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
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
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
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
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
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
40、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
41、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
42、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
43、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)
44、查询各学生的年龄，只按年份来算
select sid, sname以上是关于经典50道SQL练习题的主要内容，如果未能解决你的问题，请参考以下文章