mysql 查詢面試題 練習題 權亮

面試發現對查詢的理解還不夠，就繼續做了練習，這次對查詢有了更深的理解。
如果我的答題有問題，歡迎大家跟我交流。

create table student(
sid varchar(20),
sname varchar(20) not null default ‘’,
sbirth varchar(20) not null default ‘’,
ssex varchar (10) not null default ‘’,
primary key (sid)
);

create table course(
cid varchar(20),
cname varchar(20) not null default ‘’,
tid varchar(20) not null default ‘’,
primary key (cid)
);

create table teacher (
tid varchar (20),
tname varchar (20) not null default ‘’,
primary key (tid)
);

create table score (
sid varchar(20),
cid varchar(20) not null default ‘’,
sscore int(3),
primary key (sid,cid)
);

– 插入學生表測試數據
insert into Student values(‘01’ , ‘趙雷’ , ‘1990-01-01’ , ‘男’);
insert into Student values(‘02’ , ‘錢電’ , ‘1990-12-21’ , ‘男’);
insert into Student values(‘03’ , ‘孫風’ , ‘1990-05-20’ , ‘男’);
insert into Student values(‘04’ , ‘李雲’ , ‘1990-08-06’ , ‘男’);
insert into Student values(‘05’ , ‘周梅’ , ‘1991-12-01’ , ‘女’);
insert into Student values(‘06’ , ‘吳蘭’ , ‘1992-03-01’ , ‘女’);
insert into Student values(‘07’ , ‘鄭竹’ , ‘1989-07-01’ , ‘女’);
insert into Student values(‘08’ , ‘王菊’ , ‘1990-01-20’ , ‘女’);
– 課程表測試數據
insert into Course values(‘01’ , ‘語文’ , ‘02’);
insert into Course values(‘02’ , ‘數學’ , ‘01’);
insert into Course values(‘03’ , ‘英語’ , ‘03’);

– 教師表測試數據
insert into Teacher values(‘01’ , ‘張三’);
insert into Teacher values(‘02’ , ‘李四’);
insert into Teacher values(‘03’ , ‘王五’);

– 成績表測試數據
insert into Score values(‘01’ , ‘01’ , 80);
insert into Score values(‘01’ , ‘02’ , 90);
insert into Score values(‘01’ , ‘03’ , 99);
insert into Score values(‘02’ , ‘01’ , 70);
insert into Score values(‘02’ , ‘02’ , 60);
insert into Score values(‘02’ , ‘03’ , 80);
insert into Score values(‘03’ , ‘01’ , 80);
insert into Score values(‘03’ , ‘02’ , 80);
insert into Score values(‘03’ , ‘03’ , 80);
insert into Score values(‘04’ , ‘01’ , 50);
insert into Score values(‘04’ , ‘02’ , 30);
insert into Score values(‘04’ , ‘03’ , 20);
insert into Score values(‘05’ , ‘01’ , 76);
insert into Score values(‘05’ , ‘02’ , 87);
insert into Score values(‘06’ , ‘01’ , 31);
insert into Score values(‘06’ , ‘03’ , 34);
insert into Score values(‘07’ , ‘02’ , 89);
insert into Score values(‘07’ , ‘03’ , 98);

select * FROM student;
select * from teacher;
select * from course;
select * from score;
use ceshi;

– 查詢課程1成績第二高的學生.
select * from score where cid=01 order by sscore desc limit 1,1;
select * from score where cid=01 order by sscore desc ;

select a.*, (select count( distinct sscore)+1
from score b where b.cid=a.cid and b.sscore>a.sscore) rank
from score a order by cid asc,sscore desc;

select a.*, (select count( distinct sscore)+1
from score b where b.cid=a.cid and b.sscore>a.sscore) rank
from score a where (select count( distinct sscore)+1
from score b where b.cid=a.cid and b.sscore>a.sscore)=3 order by cid asc,sscore desc ;

select cid,max(sscore) from score group by cid;
select group_concat(sid) ,max(sscore) from score group by cid;

select * from score a
where a.sscore >= ( select max(sscore) from score where cid=a.cid );
select max(sscore) from score group by cid;

select * from score a
where a.sscore = (select max(sscore) from score where cid=a.cid );

– 1、查詢"01"課程比"02"課程成績高的學生的信息及課程分數

select * from score;

select c.sname,a.sid,a.sscore course01,b.sscore course02 from student c, score a,score b where c.sid=a.sid and a.sid=b.sid and a.cid=01 and b.cid=02 and a.sscore>b.sscore;

select a.* ,b.sscore as 01_score,c.sscore as 02_score from
student a
join score b on a.sid=b.sid and b.cid=‘01’
left join score c on a.sid=c.sid and c.cid=‘02’ or c.cid = NULL where b.sscore>c.sscore;

select a.* ,b.,c. from student a join score b on a.sid=b.sid and b.cid=‘01’ left join score c on a.sid=c.sid and c.cid=‘02’ where b.sscore>c.sscore;

– 2、查詢"01"課程比"02"課程成績低的學生的信息及課程分數

select a.sname ,b.sscore 01score ,c.sscore 02score
from student a
join score b on a.sid=b.sid and b.cid=01
left join score c on b.sid=c.sid and c.cid=02
where b.sscore<c.sscore;

– 3、查詢平均成績大於等於60分的同學的學生編號和學生姓名和平均成績

select b.sname,a.sid,avg(a.sscore) avgs
from score a
left join student b
on a.sid=b.sid
group by a.sid
having avgs>60 ;

– 4、查詢平均成績小於60分的同學的學生編號和學生姓名和平均成績
– (包括有成績的和無成績的)
select b.sname,a.sid,avg(a.sscore) avgs
from score a
right join student b
on a.sid=b.sid
group by a.sid
having avgs<60 or avgs is null
order by avgs desc;

select b.sid,b.sname,ROUND(AVG(a.sscore),2) as avg_score from
student b
left join score a on b.sid = a.sid
GROUP BY b.sid,b.sname HAVING avg_score <60
union
select a.sid,a.sname,0 as avg_score from
student a
where a.sid not in (
select distinct sid from score);

– 5、查詢所有同學的學生編號、學生姓名、選課總數、所有課程的總成績
select a.sid,a.sname,count(b.cid) 選課總數, sum(sscore) 總成績
from student a left join score b
on a.sid=b.sid
group by a.sid;

– 6、查詢"李"姓老師的數量
select count(tname) from teacher where tname like ‘李%’;

– 7、查詢學過"張三"老師授課的同學的信息

select a.*,d.tname from student a join score b on a.sid=b.sid
right join course c on b.cid=c.cid
right join teacher d on d.tid =c.tid where d.tname=‘張三’;

– 8、查詢沒學過"張三"老師授課的同學的信息
select * from score a ,

(select a.cid from course a left join teacher b on a.tid=b.tid where b.tname=‘張三’);

select * from score;

– 9、查詢學過編號爲"01"並且也學過編號爲"02"的課程的同學的信息

select * from score a ,score b where a.sid=b.sid and a.cid=01 and b.cid=02;

– 10、查詢學過編號爲"01"但是沒有學過編號爲"02"的課程的同學的信息
use ceshi;
select b.sid,b.sname from score a join student b on a.sid=b.sid where cid=01 and a.sid not in (select sid from score where cid=02);
select * from score;

– 11、查詢沒有學全所有課程的同學的信息

select b.sname,a.sid,count(cid) c from student b
left join score a on b.sid=a.sid
group by sid
having c<(select count(cid) from course);

– 12、查詢至少有一門課與學號爲"01"的同學所學相同的同學的信息
select distinct(b.sid),b.sname,b.sbirth,b.ssex from student b join score a on a.sid=b.sid
where a.cid in (select cid from score where sid=01) and a.sid !=01;

select * from score;

– 13、查詢和"01"號的同學學習的課程完全相同的其他同學的信息

select a.sid from score a
group by a.sid having a.cid in
(select b.cid from score b where b.sid=01 ) and
count(a.cid) = (select count(c.cid) from score c where c.sid=01)
and a.sid!=01;

select * from score;
select b.cid from score b where b.sid=01;

select * from student a where a.sid in(
select b.sid from score b where b.cid in (
select cid from score where sid=01)
and sid!=01 group by sid having count(b.cid) =(select count(*) from score where sid=01));

use ceshi;

select sid from score where sid!=01 group by sid
having group_concat(cid order by cid) =
(select group_concat(cid order by cid) from score where sid=01);

select sid from student where sid!=01
and sid in (select sid from score where cid
in (select cid from score where sid=01)
group by sid having count(cid)
=(select count(cid) from score where sid=01));

select * from score;

– 14、查詢沒學過"張三"老師講授的任一門課程的學生姓名
use ceshi;

select sid,sname from student
where sid not in (select sid from score where cid =
(select cid from teacher a ,course b where a.tid=b.tid and a.tname=‘張三’));

select sid from student where sid not in
(select sid,count(cid) a from score group by sid
having cid not in (select cid from score where sid=01) and
sid=!‘01’ and a!=(select count(cid) from score where sid=01));

select sid from score where sid
not in (select sid from score where cid
not in (select cid from score where sid=01) )
group by sid
having count(cid)=(select count(cid) from score where sid=01) and sid!=01;

select sid from score where cid in
(select cid from score where sid =01)
group by sid having count(cid )=(select count(cid) from score where sid=01) and sid!=01;

– 15、查詢兩門及其以上不及格課程的同學的學號，姓名及其平均成績

– 16、檢索"01"課程分數小於60，按分數降序排列的學生信息

– 17、按平均成績從高到低顯示所有學生的所有課程的成績以及平均成績

– 18.查詢各科成績最高分、最低分和平均分：以如下形式顯示：課程ID，課程name，最高分，最低分，平均分，及格率，中等率，優良率，優秀率
select cid ,max(sscore),min(sscore),avg(sscore),count(sscore),
sum(case when sscore >=60 then 1 else 0 end )/ count(sscore) 及格率,
sum(case when sscore >=70 and sscore< 80 then 1 else 0 end )/ count(sscore) 中等率,
sum(case when sscore >=80 and sscore< 90 then 1 else 0 end )/ count(sscore) 優良率,
sum(case when sscore >=90 and sscore <=100 then 1 else 0 end )/ count(sscore) 優秀率
from score group by cid;

select * from score where cid=01;
select * from score where cid=02;
select * from score where cid=03;
select cid,count(sscore) from score group by cid;

– 19、按各科成績進行排序，並顯示排名
select sid ,cid,sscore,
(select count(sscore)+1 from score a where a.cid=b.cid and a.sscore>b.sscore) rank
from score b order by cid asc, sscore desc;

select sid ,cid,sscore,
(select count(distinct sscore)+1 from score a where a.cid=b.cid and a.sscore>b.sscore) rank
from score b order by cid asc, sscore desc;

– 20、查詢學生的總成績並進行排名

select sid ,sum(sscore) tot from score
group by sid order by tot desc;

– 21、查詢不同老師所教不同課程平均分從高到低顯示

select cid,avg(sscore) av from score
group by cid order by av desc;

– 22、查詢所有課程的成績第2名到第3名的學生信息及該課程成績

select sname, a.sid,cid,sscore ,
(select count(sscore)+1 from score c where c.cid=b.cid and c.sscore>b.sscore) rank
from student a ,score b
where a.sid=b.sid
and (select count(sscore)+1 from score c where c.cid=b.cid and c.sscore>b.sscore) <4
order by cid asc ,sscore desc ;

select a.,b., count(b.cid) rank from score a
left join score b on a.cid = b.cid and a.sscore<b.sscore order by a.cid asc,a.sscore desc;

select a.,b., count( distinct b.sscore)+1 rank from score a
left join score b on a.cid = b.cid and a.sscore<b.sscore
group by a.cid, a.sid order by a.cid asc,a.sscore desc;

select a.,b., count(distinct b.sscore)+1 rank from score a
left join score b on a.cid = b.cid and a.sscore<b.sscore
group by a.cid, a.sid having rank between 2 and 3 order by a.cid asc,a.sscore desc;

– 23、統計各科成績各分數段人數：課程編號,課程名稱,[100-85],[85-70],[70-60],[0-60]及所佔百分比
select count(a.sid), a.cid, cname,count(sscore),
sum(case when sscore>=0 and sscore <=60 then 1 else 0 end )/count(sscore) as '[0-60]所佔百分比 ',
sum(case when sscore>60 and sscore <=70 then 1 else 0 end )/count(sscore) as ‘[70-60]所佔百分比’ ,
sum(case when sscore>70 and sscore <=85 then 1 else 0 end )/count(sscore) as ‘[70-85]所佔百分比’ ,
sum(case when sscore>85 and sscore <=100 then 1 else 0 end )/count(sscore) ‘[85-100]所佔百分比’
from score a,course b
where a.cid=b.cid
group by cid;

select * from score order by cid;

– 24、查詢學生平均成績及其名次
select sid,avg(sscore) from score group by sid
order by avg(sscore) desc;

select sscore from score where sid=01;

– 25、查詢各科成績前三名的記錄
– 1.選出b表比a表成績大的所有組
– 2.選出比當前id成績大的 小於三個的

– 26、查詢每門課程被選修的學生數
select count(sid) from score
group by cid;

– 27、查詢出只有兩門課程的全部學生的學號和姓名

select a.sid,sname,count(cid) from score a ,student b where a.sid=b.sid
group by sid having count(cid )=2 ;

– 28、查詢男生、女生人數

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

– 29、查詢名字中含有"風"字的學生信息

select * from student where sname like ‘%風%’;

– 30、查詢同名同性學生名單，並統計同名人數
use ceshi;
select * from student;
select a.ssex,a.sname,b.* from student a,student b where a.ssex=b.ssex and a.sname=b.sname and a.sid!=b.sid;

select a.sname,a.ssex,count(*) from student a  JOIN 
				student b on a.sid !=b.sid and a.sname = b.sname and a.ssex = b.ssex
	GROUP BY a.sname,a.ssex;

– 31、查詢1990年出生的學生名單
select * from student where year(sbirth)=1990;

– 32、查詢每門課程的平均成績，結果按平均成績降序排列，平均成績相同時，按課程編號升序排列

select cid, avg(sscore) a from score group by cid order by a desc,cid asc;

– 33、查詢平均成績大於等於85的所有學生的學號、姓名和平均成績
select a.sid,b.sname,avg(a.sscore) c from score a ,student b where a.sid=b.sid group by b.sid having c>=85;

– 34、查詢課程名稱爲"數學"，且分數低於60的學生姓名和分數

select a.sname,a.sid,b.sscore
from student a ,score b,course c
where a.sid=b.sid and b.cid=c.cid and c.cname=‘數學’ and b.sscore<60;

select * from course;

– 35、查詢所有學生的課程及分數情況；
select a.sid,c.sname,
sum(case when b.cname=‘語文’ then a.sscore else 0 end ) 語文,
sum(case when b.cname=‘數學’ then a.sscore else 0 end) 數學,
sum(case when b.cname=‘英語’ then a.sscore else 0 end ) 英語
from score a,course b,student c
where a.cid=b.cid and a.sid=c.sid
group by a.sid;

		select a.sid,c.sname,
(case when b.cname='語文' then a.sscore else 0 end ) 語文,
(case when b.cname='數學' then a.sscore else 0 end) 數學,
(case when b.cname='英語' then a.sscore else 0 end ) 英語
from score a,course b,student c 
where a.cid=b.cid and a.sid=c.sid;

select * from score;

– 36、查詢任何一門課程成績在70分以上的姓名、課程名稱和分數；
select sname,a.sid,group_concat(cname) from student a, score b,course c
where a.sid=b.sid and b.cid=c.cid
and a.sid not in ( select sid from score where sscore<70 )
group by sid;

select * from score;

– 37、查詢不及格的課程
select cid from score where sscore<60 group by cid;

– 38、查詢課程編號爲01且課程成績在80分以上的學生的學號和姓名；

select a.sid,a.sname,b.sscore
from student a ,score b
where a.sid=b.sid
and b.cid=01 and b.sscore>80;
select * from score where cid =01;

– 39、求每門課程的學生人數

select cid, count(sid) from score group by cid;
use ceshi;

– 40、查詢選修"張三"老師所授課程的學生中，成績最高的學生信息及其成績
select a.*,max(b.sscore)
from student a , score b ,course c ,teacher d
where a.sid=b.sid and b.cid=c.cid and c.tid=d.tid and tname=‘張三’ group by b.cid;

– 41、查詢不同課程成績相同的學生的學生編號、課程編號、學生成績
select * from score a ,score b where a.sscore=b.sscore and a.cid!=b.cid;

– 42、查詢每門功成績最好的前兩名
select sid,cid,sscore,(select count(sscore)+1 from score a where a.cid=b.cid and a.sscore>b.sscore) rank
from score b
where (select count(sscore)+1 from score a where a.cid=b.cid and a.sscore>b.sscore)❤️
order by cid asc,sscore desc;

– 43、統計每門課程的學生選修人數（超過5人的課程才統計）。要求輸出課程號和選修人數，查詢結果按人數降序排列，若人數相同，按課程號升序排列
select cid ,if(count()>5,count(),null) rank
from score
group by cid
order by rank desc,cid asc;

– 44、檢索至少選修兩門課程的學生學號

select sid from student
where sid
in (select sid from score group by sid
having count(cid)>=2);

select * from score;

– 45、查詢選修了全部課程的學生信息

select sid from student
where sid in
(select sid from score group by sid having count(cid)=(select count(*) from course));

– 46、查詢各學生的年齡
– 按照出生日期來算，當前月日 < 出生年月的月日則，年齡減一

select year(from_days( datediff(curdate(),sbirth))) from student;
select * from student;
select sid,timestampdiff(year,sbirth,curdate()) from student;

– 47、查詢本週過生日的學生
select 7-(dayofweek(curdate())-1);
select date_format( sbirth) from student;
use ceshi;
select * from student where week(date_format(sbirth,’%y-=%m-%d’))=week(curdate())+1;

  select * from student where week(sbirth)=week(curdate()); 

select curdate();
select week(sbirth) from student;

– 48、查詢下週過生日的學生

select * from student where week(sbirth)=week(curdate())+1;
– 49、查詢本月過生日的學生
select * from student where month(sbirth)=month(curdate());

– 50、查詢下月過生日的學生
select * from student where month(sbirth)=month(curdate())+1;