oracle的ROW_NUMBER() OVER函数的基本用法

 转自：http://www.cnblogs.com/icebutterfly/archive/2009/08/05/1539657.html

 语法：ROW_NUMBER() OVER(PARTITION BY COLUMN ORDER BY COLUMN)

 

row_number() OVER (PARTITION BY COL1 ORDER BY COL2) 表示根据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)

 

例子1：row_number中有1,2,3等数字

SElECT row_number() over(partition by b.agency_item_id, c.processinst_id order by c.createdate desc) row_num,
                    b.agency_item_id,
                    b.agency_id,
                    d.*
               FROM tb_bgt_dept_status b
               join tb_bgt_ref_dept_wf c
                 on b.id = c.bgt_wf_id
               join v_wf_working d
                 on c.processinst_id = d.PROCINSTID
              where b.annual = 2016

注意：例1的图见下面

 

 

 

例子2：都是数字1

SElECT row_number() over(partition by b.agency_item_id, c.processinst_id order by c.createdate desc) row_num,
                    b.agency_item_id,
                    b.agency_id,
                    d.*
               FROM tb_bgt_dept_status b
               join tb_bgt_ref_dept_wf c
                 on b.id = c.bgt_wf_id
               join v_wf_working d
                 on c.processinst_id = d.PROCINSTID
              where b.annual = 2016

)where row_num=1

注意：例子2见图2