over(partition by)开窗函数简介

简单举例：

SELECT code,kpi_type,plan_value_num,

row_number()over(partition by code,kpi_type order by plan_value_num desc)rowno  FROM  fs_target_yp_kpi 

分析：

code,kpi_type,plan_value_num 记录后面开窗函数后的规律值

partition by code,kpi_type 按照这两列分组

order by plan_value_num desc 按照此字段降序排序

row_number() 记录每组排序后编号

http://blog.itpub.net/27042095/viewspace-768880/