MySQL查询语句练习50题+答案
50题目录
-
- 首先分别建表和插入数据
- 1、查询“001”课程比“002”课程成绩高的所有学生的学号；
- 2、查询平均成绩大于60分的同学的学号和平均成绩；
- 3、查询所有同学的学号、姓名、选课数、总成绩；
- 4、查询姓“李”的老师的个数；
- 5、查询没学过“叶平”老师课的同学的学号、姓名；
- 6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；
- 7、查询学过“叶平”老师所教的所有课的同学的学号、姓名；
- 8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名；
- 9、查询所有课程成绩小于60分的同学的学号、姓名； #注意关键词所有课程，可以采用逆向思维
- 10、查询没有学全所有课的同学的学号、姓名；
- 11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名；
- 12、查询与“1001”同学所学课程相同的其他同学学号和姓名；
- 13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩；
- 14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名；
- 15、删除学习“叶平”老师课的SC表记录；
- 16、向SC表中插入一些记录，这些记录要求符合以下条件：没有上过编号“003”课程的同学学号、’002’号课的平均成绩；
- 17、按平均成绩从高到低显示所有学生的“JAVA”、“C#”、“C++”三门的课程成绩，按如下形式显示： 学生ID,,C#,C++,JAVA,有效课程数,有效平均分
- 18、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;
- 19、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 ；
- 20、查询如下课程平均成绩和及格率的百分数(用”1行”显示): 企业管理（001），马克思（002），OO&UML （003），数据库（004）
- 21、查询不同老师所教不同课程平均分从高到低显示
- 22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（001），马克思（002），UML （003），数据库（004） [学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩
- 23、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]
- 24、查询学生平均成绩及其名次
- 25、查询各科成绩前三名的记录:(不考虑成绩并列情况)
- 26、查询每门课程被选修的学生数
- 27、查询出只选修了一门课程的全部学生的学号和姓名
- 28、查询男生、女生人数
- 29、查询姓“张”的学生名单
- 30、查询同名同性学生名单，并统计同名人数
- 31、1981年出生的学生名单(注：Student表中Sage列的类型是datetime)
- 32、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
- 33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩
- 34、查询课程名称为“数据库”，且分数低于60的学生姓名和分数
- 35、查询所有学生的选课情况；
- 36、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；
- 37、查询不及格的课程，并按课程号从大到小排列
- 38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名；
- 39、求选了课程的学生人数
- 40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩
- 41、查询各个课程及相应的选修人数
- 42、查询不同课程成绩相同的学生的学号、课程号、学生成绩
- 43、查询每门功成绩最好的前两名
- 44、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，查询结果按人数降序排列，若人数相同，按课程号升序排列
- 45、检索至少选修两门课程的学生学号
- 46、查询全部学生都选修的课程的课程号和课程名
- 47、查询没学过“叶平”老师讲授的任一门课程的学生姓名
- 48、查询两门以上不及格课程的同学的学号及其平均成绩
- 49、检索“004”课程分数小于60，按分数降序排列的同学学号
- 50、删除“002”同学的“001”课程的成绩
需要用的表的信息如下：
1.学生表：student（编号sid，姓名sname，年龄sage，性别ssex)
2.课程表：course（课程编号cid，课程名称cname，教师编号tid）
3.成绩表：sc（学生编号sid，课程编号cid，成绩score）
4.教师表：teacher（教师编号tid，姓名tname）
首先分别建表和插入数据
student表
create table Student(SId varchar(10),Sname varchar(10),Sage varchar(10),Ssex varchar(10));
insert into Student values('1001' , '张三' , '19' , '男');
insert into Student values('1002' , '李四' , '20' , '女');
insert into Student values('1003' , '王五' , '21' , '男');
insert into Student values('1004' , '马六' , '19' , '女');
insert into Student values('1005' , '孙七' , '22' , '女');
insert into Student values('1006' , '钱八' , '18' , '男');
insert into Student values('1007' , '赵九' , '23' , '女');
insert into Student values('1008' , '罗晶晶' , '21' , '女');
course表
create table Course(CId varchar(10),Cname varchar(10),TId varchar(10));
insert into Course values('001' , 'PHP' , '1');
insert into Course values('002' , 'C#' , '1');
insert into Course values('003' , 'C++' , '2');
insert into Course values('004' , 'JAVA' , '3');
insert into Course values('005' , 'Python' , '4');
insert into Course values('006' , 'R' , '5');
insert into Course values('007' , 'HTML' , '6');
teacher表
create table Teacher(TId varchar(10),Tname varchar(10));
insert into Teacher values('1' , '叶平');
insert into Teacher values('2' , '李浩然');
insert into Teacher values('3' , '胡平原');
insert into Teacher values('4' , '朱清时');
insert into Teacher values('5' , '赛先生');
insert into Teacher values('6' , '宋三东');
sc表
create table SC(SId varchar(10),CId varchar(10),score decimal(18,1));
insert into SC values('1001' , '001' , 89);
insert into SC values('1002' , '001' , 80);
insert into SC values('1003' , '001' , 30);
insert into SC values('1004' , '001' , 78);
insert into SC values('1005' , '001' , 68);
insert into SC values('1006' , '001' , 93);
insert into SC values('1007' , '001' , 62);
insert into SC values('1001' , '002' , 67);
insert into SC values('1002' , '002' , 86);
insert into SC values('1003' , '002' , 67);
insert into SC values('1004' , '002' , 77);
insert into SC values('1005' , '002' , 66);
insert into SC values('1006' , '002' , 84);
insert into SC values('1007' , '002' , 72);
insert into SC values('1001' , '003' , 82);
insert into SC values('1002' , '003' , 85);
insert into SC values('1003' , '003' , 32);
insert into SC values('1004' , '003' , 73);
insert into SC values('1005' , '003' , 64);
insert into SC values('1006' , '003' , 87);
insert into SC values('1007' , '003' , 77);
insert into SC values('1008' , '003' , 94);
insert into SC values('1001' , '004' , 39);
insert into SC values('1002' , '004' , 80);
insert into SC values('1003' , '004' , 80);
insert into SC values('1004' , '004' , 88);
insert into SC values('1005' , '004' , 68);
insert into SC values('1006' , '004' , 59);
insert into SC values('1007' , '004' , 42);
insert into SC values('1008' , '004' , 64);
insert into SC values('1001' , '005' , 89);
insert into SC values('1002' , '005' , 70);
insert into SC values('1003' , '005' , 60);
insert into SC values('1004' , '005' , 58);
insert into SC values('1005' , '005' , 38);
insert into SC values('1006' , '005' , 89);
insert into SC values('1007' , '005' , 72);
insert into SC values('1008' , '005' , 64);
insert into SC values('1001' , '006' , 49);
insert into SC values('1002' , '006' , 90);
insert into SC values('1003' , '006' , 70);
insert into SC values('1004' , '006' , 48);
insert into SC values('1005' , '006' , 98);
insert into SC values('1006' , '006' , 59);
insert into SC values('1007' , '006' , 72);
insert into SC values('1008' , '006' , 74);
insert into SC values('1001' , '007' , 100);
insert into SC values('1002' , '007' , 99);
insert into SC values('1003' , '007' , 89);
insert into SC values('1004' , '007' , 88);
insert into SC values('1005' , '007' , 78);
insert into SC values('1006' , '007' , 99);
insert into SC values('1007' , '007' , 82);
1、查询“001”课程比“002”课程成绩高的所有学生的学号；
select a.sid from
(select sid,score from SC where cid='001') a,
(select sid,score from SC where cid='002') b
where a.score>b.score and a.sid=b.sid;
2、查询平均成绩大于60分的同学的学号和平均成绩；
select sid ,avg(score) from sc
group by sid having avg(score)>60;
3、查询所有同学的学号、姓名、选课数、总成绩；
select student.sid,student.sname,count(sc.cid),sum(score)
from student left outer join sc on student.sid=sc.sid
group by student.sid,sname;
4、查询姓“李”的老师的个数；
#需要去重
select count(distinct(tname))
from teacher where tname like '李%';
5、查询没学过“叶平”老师课的同学的学号、姓名；
select student.sid,student.sname
from student
where sid not in (select distinct(sc.sid) from sc,course,teacher
where sc.cid=course.cid and
teacher.tid=course.tid and
teacher.tname='叶平');
6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；
select student.sid,student.sname
from student,sc
where student.sid=sc.sid
and sc.cid='001'
and exists (select * from sc as sc2 where sc2.sid=sc.sid
and sc2.cid='002');
7、查询学过“叶平”老师所教的所有课的同学的学号、姓名；
select sid,sname from student
where sid in (select sid from sc,course,teacher where sc.cid=course.cid
and teacher.tid=course.tid and teacher.tname='叶平'
group by sid having count(sc.cid)=
(select count(cid) from course,teacher
where teacher.tid=course.tid and tname='叶平'));
8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名；
select sid,sname
from (select student.sid,student.sname,score,
(select score from sc sc2
where sc2.sid=student.sid
and sc2.cid='002') score2
from student,sc
where student.sid=sc.sid and cid='001') sc3
where score2<score;
9、查询所有课程成绩小于60分的同学的学号、姓名； #注意关键词所有课程，可以采用逆向思维
select sid,sname from student
where sid not in
(select student.sid from student,sc
where student.sid=sc.sid and score>60);
10、查询没有学全所有课的同学的学号、姓名；
select student.sid,student.sname
from student,sc
where student.sid=sc.sid
group by student.sid,student.sname having count(cid)<(select count(cid)from course);
11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名；
#写法一
select sid,sname from student
where sid in
(select distinct sid from sc where cid in (select cid from sc where sid='1001'));
#写法二
select distinct st.sid,sname from student st
inner join sc on st.sid=sc.sid
where sc.cid in (select cid from sc where sid='1001');
12、查询与“1001”同学所学课程相同的其他同学学号和姓名；
select distinct sc.sid,sname
from student, sc
where student.sid= sc.sid
and cid in (select cid from sc where sid='1001');
13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩；
update sc set score=(select avg( sc_2.score)
from sc sc_2
where sc_2.cid= sc.cid )
from course,teacher
where course.cid= sc.cid
and course.tid=teacher.tid
and teacher.tname='叶平');
14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名；
select sid from sc where cid in
(select cid from sc where sid='1002')
group by sid having count(*)=
(select count(*) from sc where sid='1002');
15、删除学习“叶平”老师课的SC表记录；
delete sc
from course,teacher,sc
where course.cid= sc.cid
and course.tid= teacher.tid
and tname='叶平';
16、向SC表中插入一些记录，这些记录要求符合以下条件：没有上过编号“003”课程的同学学号、’002’号课的平均成绩；
insert sc select sid,'002',
(select avg(score)from sc where cid='002')
from student where sid not in
(select sid from sc where cid='002');
17、按平均成绩从高到低显示所有学生的“JAVA”、“C#”、“C++”三门的课程成绩，按如下形式显示： 学生ID,C#,C++,JAVA,有效课程数,有效平均分
select sid as 学生id
,(select score from sc where sc.sid=t.sid and cid='004') as 数据库
,(select score from sc where sc.sid=t.sid and cid='001') as 企业管理
,(select score from sc where sc.sid=t.sid and cid='006') as 英语
,count(*) as 有效课程数, avg(t.score) as 平均成绩
from sc as t
group by sid
order by avg(t.score) ;
18、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 l.cid as 课程id,l.score as 最高分,r.score as 最低分
from sc l , sc as r
where l.cid = r.cid and
l. score = (select max(il.score)
from sc as il,student as im
where l.cid = il.cid and im. sid=il.sid
group by il.cid)
and r. score = (select min(ir.score)
from sc as ir
where r.cid = ir.cid
group by ir.cid );
19、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 t.cid as 课程号,
max(course.cname)as 课程名,
isnull(avg(score),0) as 平均成绩,
100 * sum(case when isnull(score,0)>=60 then 1 else 0
end)/count(*) as 及格百分数
from sc teac,course
where t.cid=course.cid
group by t.cid
order by 100 * sum(case when isnull(score,0)>=60 then 1
else 0 end)/count(*) desc；
20、查询如下课程平均成绩和及格率的百分数(用”1行”显示): 企业管理（001），马克思（002），OO&UML （003），数据库（004）
select sum(case when cid ='001' then score else 0 end)/sum(case cid when '001' then 1 else 0 end) as 企业管理平均分
,100 * sum(case when cid ='001' and score >= 60 then 1 else 0 end)/sum(case when cid ='001' then 1 else 0 end) as 企业管理及格百分数
,sum(case when cid ='002' then score else 0 end)/sum(case cid when '002' then 1 else 0 end) as 马克思平均分
,100 * sum(case when cid ='002' and score >= 60 then 1 else 0 end)/sum(case when cid ='002' then 1 else 0 end) as 马克思及格百分数
,sum(case when cid ='003' then score else 0 end)/sum(case cid when '003' then 1 else 0 end) as uml平均分
,100 * sum(case when cid ='003' and score >= 60 then 1 else 0 end)/sum(case when cid ='003' then 1 else 0 end) as uml及格百分数
,sum(case when cid ='004' then score else 0 end)/sum(case cid when '004' then 1 else 0 end) as 数据库平均分
,100 * sum(case when cid ='004' and score >= 60 then 1 else 0 end)/sum(case when cid ='004' then 1 else 0 end) as 数据库及格百分数
from sc;
21、查询不同老师所教不同课程平均分从高到低显示
select max(z.tid) as 教师id,
max(z.tname) as 教师姓名,c.cid as 课程id,
max(c.cname) as 课程名称,
avg(score) as 平均成绩
from sc as t,course as c ,teacher as z
where t.cid=c.cid and c.tid=z.tid
group by c.cid
order by avg(score) desc;
22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（001），马克思（002），UML （003），数据库（004） [学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩
select distinct top 3
sc.sid as 学生学号,
student.sname as 学生姓名 ,
t1.score as 企业管理,
t2.score as 马克思,
t3.score as uml,
t4.score as 数据库,
isnull(t1.score,0) + isnull(t2. score,0) + isnull(t3. score,0) + isnull(t4.score,0) as 总分
from student, sc left join sc as t1
on sc.sid = t1.sid and t1.cid = '001'
left join sc as t2
on sc.sid = t2.sid and t2.cid = '002'
left join sc as t3
on sc.sid = t3.sid and t3.cid = '003'
left join sc as t4
on sc.sid = t4.sid and t4.cid = '004'
where student. sid= sc.sid and
isnull(t1.score,0) + isnull(t2.score,0) + isnull(t3.score,0) + isnull(t4.score,0)
not in
(select distinct
top 15 with ties
isnull(t1.score,0) + isnull(t2.score,0) + isnull(t3.score,0) + isnull(t4.score,0)
from sc
left join sc as t1
on sc.sid = t1.sid and t1.cid = 'k1'
left join sc as t2
on sc.sid = t2.sid and t2.cid = 'k2'
left join sc as t3
on sc.sid = t3.sid and t3.cid = 'k3'
left join sc as t4
on sc.sid = t4.sid and t4.cid = 'k4'
order by isnull(t1.score,0) + isnull(t2.score,0) + isnull(t3.score,0) + isnull(t4.score,0) desc);
23、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.cid as 课程id, cname as 课程名称
,sum(case when score between 85 and 100 then 1 else 0 end) as [100 - 85]
,sum(case when score between 70 and 85 then 1 else 0 end) as [85 - 70]
,sum(case when score between 60 and 70 then 1 else 0 end) as [70 - 60]
,sum(case when score < 60 then 1 else 0 end) as [60 -]
from sc,course
where sc.cid=course.cid
group by sc.cid,cname;
24、查询学生平均成绩及其名次
select 1+(select count(distinct 平均成绩)
from (select sid,avg(score) as 平均成绩
from sc
group by sid) as t1
where 平均成绩>t2.平均成绩) as 名次,
sid as 学生学号,平均成绩
from (select sid,avg(score) 平均成绩
from sc
group by sid) as t2
order by 平均成绩 desc;
25、查询各科成绩前三名的记录:(不考虑成绩并列情况)
select t1.sid as 学生id,t1.cid as 课程id, score as 分数
from sc t1
where score in (select top 3 score
from sc
where t1.cid= cid
order by score de sc)
order by t1.cid;
26、查询每门课程被选修的学生数
select cid,count(sid) from sc group by cid;
27、查询出只选修了一门课程的全部学生的学号和姓名
select sc.sid,student.sname,count(cid) as 选课数
from sc,student
where sc.sid=student.sid
group by sc.sid,student.sname having count(cid)=1;
28、查询男生、女生人数
select count(ssex) as 男生人数
from student
group by ssex having ssex='男';
select count(ssex) as 女生人数
from student
group by ssex having ssex='女'；
29、查询姓“张”的学生名单
select sname from student where sname like '张%';
30、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;
31、1981年出生的学生名单(注：Student表中Sage列的类型是datetime)
select sname,convert(char (11),datepart(year,sage)) as age
from student
where convert(char(11),datepart(year,sage))='1981';
32、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 cid,avg(score)
from sc
group by cid order by avg(score),cid desc ;
33、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 sname,sc.sid,avg(score)
from student,sc
where student.sid= sc.sid
group by sc.sid,sname having avg(score)>85;
34、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 sname,isnull(score,0)
from student,sc,course
where sc.sid=student.sid
and sc.cid=course.cid
and course.cname='数据库'
and score<60;
35、查询所有学生的选课情况；
select sc.sid, sc.cid,sname,cname
from sc,student,course
where sc.sid=student.sid
and sc.cid=course.cid ;
36、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 distinct student.sid,student.sname,sc.cid, sc.score
from student, sc
where sc.score>=70
and sc.sid=student.sid;
37、查询不及格的课程，并按课程号从大到小排列
select cid from sc where score<60 order by cid ;
38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名；
select sc.sid,student.sname
from sc,student
where sc.sid=student.sid
and score>80
and cid='003';
39、求选了课程的学生人数
select count(*) from sc;
40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩
select student.sname,score
from student, sc,course c,teacher
where student.sid= sc.sid
and sc.cid=c.cid and c.tid=teacher.tid
and teacher.tname='叶平'
and sc.score=(select max(score)from sc where cid=c.cid );
41、查询各个课程及相应的选修人数
select count(*) from sc group by cid;
42、查询不同课程成绩相同的学生的学号、课程号、学生成绩
select distinct a.sid,b.score
from sc a,sc b
where a.score=b. score and a.cid <>b.cid ;
43、查询每门功成绩最好的前两名
select t1.sid as 学生id,t1.cid as 课程id, score as 分数
from sc t1
where score in (select top 2 score
from sc
where t1.cid= cid
order by score desc)
order by t1.cid;
44、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，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 as 课程号,count(*) as 人数
from sc
group by cid
order by count(*) desc,cid;
45、检索至少选修两门课程的学生学号
select sid
from sc
group by sid having count(*)>= 2;
46、查询全部学生都选修的课程的课程号和课程名
select cid,cname
from course
where cid in (select cid from sc group by cid);
47、查询没学过“叶平”老师讲授的任一门课程的学生姓名
select sname from student
where sid not in
(select sid from course,teacher,sc
where course.tid=teacher.tid
and sc.cid=course.cid and tname='叶平');
48、查询两门以上不及格课程的同学的学号及其平均成绩
select sid,avg(isnull(score,0)) from sc
where sid in
(select sid from sc
where score <60
group by sid having count(*)>2)
group by sid;
49、检索“004”课程分数小于60，按分数降序排列的同学学号
select sid from sc where cid='004'
and score <60 order by score de sc;
50、删除“002”同学的“001”课程的成绩
delete from sc where sid='002'and cid='001';