sqlserver巧用row_number和partition by分组取top数据

--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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posted @ 2014-08-22 00:39  KeenLeung  阅读(576)  评论(0编辑  收藏  举报