Oracle partition by 使用說明

--用法詳解

 

0、select * from wmg_test;     ---測試數據

 

1、select v1,v2,sum(v2) over(order by v2) as sum     --按照 v2排序，累計n+n-1+....+1

from wmg_test;

 

2、select v1,v2,sum(v2) over(partition by v1 order by v2) as sum     --先分組，組內在進行 1 中的操作

from wmg_test;

 

 

3、select v1,v2,sum(v2) over(partition by v1 order by v1) as sum   ---穩定排序

from wmg_test;

 

 

4、select v1,v2,sum(v2) over(partition by v1) as sum    --相同key的進行回填處理，沒有order by

from wmg_test;

 

 

5、select distinct v1,sum_01                                        --取一條

from (

select v1,sum(v2) over(partition by v1) as sum_01

from wmg_test

) a;

 

 

6、當然也可以逆序累加，只需order by desc 即可

 

總結區別：group by 和partition by的區別

group 單純分組

partition 也能分組，但還具備累計的功能

 

7、max ... partition by  

 通sum ... partition by ，從第一條到當前的最大值

Select Pty_Id,
                              Data_Dt,
                              Fin_In,
                              Max(Fin_In) Over(Partition By Pty_Id Order By Data_Dt) As Max_Cost from