總結：
group 單純分組
partition 也能分組，但還具備累計的功能
order by 排序，與計算函數聯用，需要累加計算
0、select * from test; ---測試資料
1、select v1,v2,sum(v2) over(order by v2) as sum from test; --按照 v2排序，累計n+n-1+....+1
2、select v1,v2,sum(v2) over(partition by v1 order by v2) as sum from test; --先分組，組内在進行 1 中的操作
3、select v1,v2,sum(v2) over(partition by v1 order by v1) as sum from test; ---穩定排序
4、select v1,v2,sum(v2) over(partition by v1) as sum from test; --相同key的進行回填處理
5、select distinct v1,sum_01 --取一條
from (
select v1,sum(v2) over(partition by v1) as sum_01
from test
) a;
6、當然也可以逆序累加，隻需order by desc 即可