SQL 面试题目及答案
学生成绩表(stuscore)：
姓名：name 课程：subject 分数：score 学号：stuid
张三 数学 89 1
张三 语文 80 1
张三 英语 70 1
李四 数学 90 2
李四 语文 70 2
李四 英语 80 2
1.计算每个人的总成绩并排名(要求显示字段：姓名，总成绩)
答案：select name,sum(score) as allscore from stuscore group by name order by allscore
2.计算每个人的总成绩并排名(要求显示字段: 学号，姓名，总成绩)
答案：select distinct t1.name,t1.stuid,t2.allscore from stuscore t1,( select stuid,sum(score) as allscore from stuscore group by stuid)t2 where t1.stuid=t2.stuidorder by t2.allscore desc
3.计算每个人单科的最高成绩(要求显示字段: 学号，姓名，课程，最高成绩)
答案：select t1.stuid,t1.name,t1.subject,t1.score from stuscore t1,(select stuid,max(score) as maxscore from stuscore group by stuid) t2 where t1.stuid=t2.stuid and t1.score=t2.maxscore
4.计算每个人的平均成绩（要求显示字段: 学号，姓名，平均成绩）
答案：select distinct t1.stuid,t1.name,t2.avgscore from stuscore t1,(select stuid,avg(score) as avgscore from stuscore group by stuid) t2 where t1.stuid=t2.stuid
5.列出各门课程成绩最好的学生(要求显示字段: 学号，姓名,科目，成绩)
答案：select t1.stuid,t1.name,t1.subject,t2.maxscore from stuscore t1,(select subject,max(score) as maxscore from stuscore group by subject) t2 where t1.subject=t2.subject and t1.score=t2.maxscore
6.列出各门课程成绩最好的两位学生(要求显示字段: 学号，姓名,科目，成绩)
答案：select distinct t1.* from stuscore t1 where t1.id in (select top 2 stuscore.id from stuscore where subject = t1.subject order by score desc) order by t1.subject
7.统计如下：学号 姓名 语文 数学 英语 总分 平均分
答案：select stuid as 学号,name as 姓名,sum(case when subject=’语文’ then score else 0 end) as 语文,sum(case when subject=’数学’ then score else 0 end) as 数学,sum(case when subject=’英语’ then score else 0 end) as 英语,sum(score) as 总分,(sum(score)/count(*)) as 平均分from stuscoregroup by stuid,name order by 总分desc
8．列出各门课程的平均成绩（要求显示字段：课程，平均成绩）
答案：select subject,avg(score) as avgscore from stuscore group by subject
9．列出数学成绩的排名（要求显示字段：学号，姓名，成绩，排名）
答案：
declare @tmp table(pm int,name varchar(50),score int,stuid int)
insert into @tmp select null,name,score,stuid from stuscore where subject=’数学’ order by score desc
declare @id int
set @id=0;
update @tmp set @id=@id+1,pm=@id
select * from @tmp
oracle:
select DENSE_RANK () OVER(order by score desc) as
row,name,subject,score,stuid from stuscore where subject=’数学’order by
score desc
ms sql(最佳选择)
select (select count(*) from stuscore t1
where subject ='数学' and t1.score>t2.score)+1 as row ,stuid,name,score
from stuscore t2 where subject ='数学' order by score desc
10．列出数学成绩在2-3名的学生（要求显示字段：学号，姓名,科目，成绩）
答案：select t3.* from(select top 2 t2.* from (select top 3 name,subject,score,stuid from stuscore where subject='数学' order by score desc) t2 order by t2.score) t3 order by t3.score desc
11．求出李四的数学成绩的排名
答案：
declare @tmp table(pm int,name varchar(50),score int,stuid int)insert into @tmp select null,name,score,stuid from stuscore where subject=’数学’ order by score descdeclare @id intset @id=0;update @tmp set @id=@id+1,pm=@idselect * from @tmp where name=’李四’
12．统计如下：课程 不及格（0-59）个 良（60-80）个 优（81-100）个
答案：select subject, (select count(*) from stuscore where score<60 and subject=t1.subject) as 不及格,(select count(*) from stuscore where score between 60 and 80 and subject=t1.subject) as 良,(select count(*) from stuscore where score >80 and subject=t1.subject) as 优 from stuscore t1 group by subject
13．统计如下：数学:张三(50分),李四(90分),王五(90分),赵六(76分)
答案：
declare @s varchar(1000)set @s=”select @s =@s+’,’+name+'(‘+convert(varchar(10),score)+’分)’ from stuscore where subject=’数学’ set @s=stuff(@s,1,1,”)print ‘数学:’+@s
14.计算科科及格的人的平均成绩
答案： select distinct t1.stuid,t2.avgscore from stuscore t1,(select
stuid,avg(score) as avgscore from stuscore group by stuid )
t2,(select stuid from stuscore where score<60 group by stuid) t3
where t1.stuid=t2.stuid and t1.stuid!=t3.stuid;
select
name,avg(score) as avgscore from stuscore s where (select sum(case
when i.score>=60 then 1 else 0 end) from stuscore i where i.name=
s.name)=3 group by name
