sql 统计查询

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

• CREATE TABLE `stuscore` (
• `id` int(11) NOT NULL auto_increment,
• `name` varchar(20) default NULL,
• `subject` varchar(20) default NULL,
• `score` varchar(20) default NULL,
• `stuid` varchar(10) default NULL,
• PRIMARY KEY (`id`)
• ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
• /*Data for the table `stuscore` */
• insert into `stuscore`(`id`,`name`,`subject`,`score`,`stuid`) values
• (1,'张三','数学','89','1'),
• (2,'张三','语文','80','1'),
• (3,'张三','英语','70','1'),
• (4,'李四','数学','90','2'),
• (5,'李四','语文','70','2'),
• (6,'李四','英语','80','2');

问题：

1. 计算每个人的总成绩并排名(要求显示字段：姓名，总成绩)

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)

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)

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）

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)

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)

7. 统计如下：

学号	姓名	语文	数学	英语	总分	平均分

8．列出各门课程的平均成绩（要求显示字段：课程，平均成绩）

9．列出数学成绩的排名（要求显示字段：学号，姓名，成绩，排名）

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）

11．求出李四的数学成绩的排名

12．统计如下：

课程	不及格（0-59）个	良（60-80）个	优（81-100）个

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：

1. 计算每个人的总成绩并排名

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

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.stuid

order by t2.allscore desc

3. 计算每个人单科的最高成绩

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

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

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

select distinct t1.* from stuscore t1

where t1.stuid in

(select top 2 stuscore.stuid from stuscore where subject = t1.subject order by score desc)

order by t1.subject

7.学号 姓名 语文 数学 英语 总分 平均分

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 stuscore

group by stuid,name

order by 总分desc

8.列出各门课程的平均成绩

select subject,avg(score) as avgscore from stuscore

group by subject

9.列出数学成绩的排名

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

select DENSE_RANK () OVER(order by score desc) as row,name,subject,score,stuid from stuscore where subject='数学'

order by score desc

declare @tmp table(pm int identity(1,1),name varchar(50),score int,stuid int)
insert into @tmp
select name,score,stuid from stuscore where subject='数学' order by score desc
select * from @tmp

10. 列出数学成绩在2-3名的学生

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

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 where name='李四'

12. 课程 不及格（-59） 良（-80） 优（-100）

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. 数学:张三(50分),李四(90分),王五(90分),赵六(76分)

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