如何根据日期范围对值进行求和并按最大日期分组？

Question

我有一个类似以下的数据集-按周和产品汇总的数量和销售额$

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对于每周，我需要对该周加上前3周的数量和销售额进行汇总

期望的结果将是：

Week    Product     Quantity    Sales
----    -------     --------    -----
1       12a         6           600
2       12a         4           400
3       12a         3           300
4       12a         1           100
5       12a         3           300 
6       12a         1           100
7       12a         4           400 
8       12a         6           600
9       12a         2           200

我觉得我需要一个循环来每周评估一次

Answer 1

使用窗口功能：

select t.*,
       sum(quantity) over (partition by product
                        order by week
                        rows between current row and 3 following
                       ) as quantity,
       sum(sales) over (partition by product
                        order by week
                        rows between current row and 3 following
                       ) as sales
from t;