SQLServer2005中的几个统计技巧

来源：http://blog.youkuaiyun.com/jinjazz/archive/2009/09/03/4516845.aspx

 

先看下面的一个表格，我们从左边的两列信息来统计出右边的结果。

在SQLServer中我们可以用over子句中来代替子查询实现来提高效率,over子句除了排名函数之外也可以和聚合函数配合。实现代码如下：

use tempdb
go
if ( object_id ( 'tb' ) is not null )
    drop table tb
go
create table tb ( name varchar ( 10 ), val int )
go
insert into tb
select 'aa' , 10
union all select 'aa' , 20
union all select 'aa' , 20
union all select 'aa' , 30
union all select 'bb' , 55
union all select 'bb' , 45
union all select 'bb' , 0

select *
, 排名 = rank () over ( partition by name order by val )
, 占比 = cast ( val * 1.0 / sum ( val ) over ( partition by name ) as decimal ( 2 , 2 ))
, 距最大 = val - max ( val ) over ( partition by name )
, 距最小 = val - min ( val ) over ( partition by name )
, 距平均 = val - avg ( val ) over ( partition by name )
from tb