面試經常碰到SQL面試題，好久沒實操已生疏？今天給大家簡單準備20道SQL經典面試題，還有下篇；喜歡可關注作者，靜候分享，溫故而知新，可以為師矣.
01 建表語句
create table Student(sid varchar(10),sname varchar(10),sage datetime,ssex nvarchar(10));
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');
create table Course(cid varchar(10),cname varchar(10),tid varchar(10));
insert into Course values('01' , '國文' , '02');
insert into Course values('02' , '數學' , '01');
insert into Course values('03' , '英語' , '03');
create table Teacher(tid varchar(10),tname varchar(10));
insert into Teacher values('01' , '張三');
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); 02 表結構預覽
--學生表
Student(SId,Sname,Sage,Ssex)
--SId 學生編号,Sname 學生姓名,Sage 出生年月,Ssex 學生性别
--課程表
Course(CId,Cname,TId)
--CId 課程編号,Cname 課程名稱,TId 教師編号
--教師表
Teacher(TId,Tname)
--TId 教師編号,Tname 教師姓名
--成績表
SC(SId,CId,score)
--SId 學生編号,CId 課程編号,score 分數
1. 查詢“01”課程比“02”課程成績高的所有學生的學号；
select distinct t1.sid as sidfrom
(select * from sc where cid='01')t1
left join
(select * from sc where cid='02')t2
on t1.sid=t2.sid
where t1.score>t2.score 2. 查詢平均成績大于60分的同學的學号和平均成績；
select
sid
,avg(score)
from sc
group by sid
having avg(score)>60 3. 查詢所有同學的學号、姓名、選課數、總成績
select
student.sid as sid
,sname
,count(distinct cid) course_cnt
,sum(score) as total_score
from student
left join sc
on student.sid=sc.sid
group by sid,sname 4. 查詢姓“李”的老師的個數；
select
count(distinct tid) as teacher_cnt
from teacher
where tname like '李%' 5. 查詢沒學過“張三”老師課的同學的學号、姓名；
select
sid,sname
from student
where sid not in
(
select
sc.sid
from teacher
left join course
on teacher.tid=course.tid
left join sc
on course.cid=sc.cid
where teacher.tname='張三'
) 6. 查詢學過“01”并且也學過編号“02”課程的同學的學号、姓名；
select
t.sid as sid
,sname
from
(
select
sid
,count(if(cid='01',score,null)) as count1
,count(if(cid='02',score,null)) as count2
from sc
group by sid
having count(if(cid='01',score,null))>0 and count(if(cid='02',score,null))>0
)t
left join student
on t.sid=student.sid 7. 查詢學過“張三”老師所教的課的同學的學号、姓名；
select
student.sid
,sname
from
(
select
distinct cid
from course
left join teacher
on course.tid=teacher.tid
where teacher.tname='張三'
)course
left join sc
on course.cid=sc.cid
left join student
on sc.sid=student.sid
group by student.sid,sname 8. 查詢課程編号“01”的成績比課程編号“02”課程低的所有同學的學号、姓名；
select
t1.sid,sname
from
(
select distinct t1.sid as sid
from
(select * from sc where cid='01')t1
left join
(select * from sc where cid='02')t2
on t1.sid=t2.sid
where t1.score>t2.score
)t1
left join student
on t1.sid=student.sid 9. 查詢所有課程成績小于60分的同學的學号、姓名；
select
t1.sid,sname
from
(
select
sid,max(score)
from sc
group by sid
having max(score<60)
)t1
left join student
on t1.sid=student.sid 10. 查詢沒有學全所有課的同學的學号、姓名；
select
t1.sid,sname
from
(
select
count(cid),sid
from sc
group by sid
having count(cid) < (select count(distinct cid) from course)
)t1
left join student
on t1.sid=student.sid 11. 查詢至少有一門課與學号為“01”的同學所學相同的同學的學号和姓名；
select
distinct sc.sid
from
(
select
cid
from sc
where sid='01'
)t1
left join sc
on t1.cid=sc.cid 12. 查詢和"01"号的同學學習的課程完全相同的其他同學的學号和姓名
#注意是和'01'号同學課程完全相同但非學習課程數相同的,這裡我用左連接配接解決這個問題select
t1.sid,sname
from
(
select
sc.sid
,count(distinct sc.cid)
from
(
select
cid
from sc
where sid='01'
)t1 #選出01的同學所學的課程
left join sc
on t1.cid=sc.cid
group by sc.sid
having count(distinct sc.cid)= (select count(distinct cid) from sc where sid = '01')
)t1
left join student
on t1.sid=student.sid
where t1.sid!='01' 13. 把“SC”表中“張三”老師教的課的成績都更改為此課程的平均成績；
#暫跳過update題目 14. 查詢沒學過"張三"老師講授的任一門課程的學生姓名
select
sname
from student
where sid not in
(
select
distinct sid
from sc
left join course
on sc.cid=course.cid
left join teacher
on course.tid=teacher.tid
where tname='張三'
) 15. 查詢兩門及其以上不及格課程的同學的學号，姓名及其平均成績
select
t1.sid,sname,avg_score
from
(
select
sid,count(if(score<60,cid,null)),avg(score) as avg_score
from sc
group by sid
having count(if(score<60,cid,null)) >=2
)t1
left join student
on t1.sid=student.sid
16. 檢索"01"課程分數小于60，按分數降序排列的學生資訊
select
sid,if(cid='01',score,100)from sc
where if(cid='01',score,100)<60
order by if(cid='01',score,100) desc 17. 按平均成績從高到低顯示所有學生的平均成績
select sid,avg(score)
from sc
group by sid
order by avg(score) desc 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
select
sc.cid
,cname
,max(score) as max_score
,min(score) as min_score
,avg(score) as avg_score
,count(if(score>=60,sid,null))/count(sid) as pass_rate
from sc
left join course
on sc.cid=course.cid
group by sc.cid 19. 按各科平均成績從低到高和及格率的百分數從高到低順序
#這裡先按照平均成績排序，再按照及格百分數排序，
select
cid
,avg(score) as avg_score
,count(if(score>=60,sid,null))/count(sid) as pass_rate
from sc
group by cid
order by avg_score,pass_rate desc 20. 查詢學生的總成績并進行排名
select
sid
,sum(score) as sum_score
from sc
group by sid
order by sum_score desc 作者：tomocat，如果侵權請聯系删除
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