sqlserver巧用row_number和partition by分组取top数据

From :  http://www.jb51.net/article/29162.htm

--1.创建测试表 

create table #score 

( 

name varchar(20), 

subject varchar(20), 

score int 

) 

--2.插入测试数据 

insert into #score(name,subject,score) values('张三','语文',98) 

insert into #score(name,subject,score) values('张三','数学',80) 

insert into #score(name,subject,score) values('张三','英语',90) 

insert into #score(name,subject,score) values('李四','语文',88) 

insert into #score(name,subject,score) values('李四','数学',86) 

insert into #score(name,subject,score) values('李四','英语',88) 

insert into #score(name,subject,score) values('李明','语文',60) 

insert into #score(name,subject,score) values('李明','数学',86) 

insert into #score(name,subject,score) values('李明','英语',88) 

insert into #score(name,subject,score) values('林风','语文',74) 

insert into #score(name,subject,score) values('林风','数学',99) 

insert into #score(name,subject,score) values('林风','英语',59) 

insert into #score(name,subject,score) values('严明','英语',96) 

--3.取每个学科的前3名数据 

select * from 

( 

select subject,name,score,ROW_NUMBER() over(PARTITION by subject order by score desc) as num from #score 

) T where T.num <= 3 order by subject 

--4.删除临时表 

truncate table #score  

drop table #score  

 

语法形式： ROW_NUMBER() OVER(PARTITION BY COL1 ORDER BY COL2) 
解释：根据COL1分组，在分组内部根据 COL2排序，而此函数计算的值就表示每组内部排序后的顺序编号（组内连续的唯一的)

 

结果：

 

 

 

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