sql - 更新行组以从行 SQL 的总和中删除特定的总金额

Question

在示例中，我想从表 2 中按 组ID。从第一行中减去的值，如果有余数，则从组中的下一行中减去(依此类推)，直到减去总计。

有没有一种方法可以做到这一点而无需遍历行来获取余数？

我的表 1:

TABLE 1 of subtracting value
GroupID    Subtracted
  1          32
  2          30

我的表 2:

ID   GroupID     ValueBefore     Reduction      ValueAfter   
 1     1             10            -10             0
 2     1             15            -15             0 
 3     1              5             -5             0 
 4     1              5             -2             3
 5     2             40            -30            10
 6     2             30              0            30

Answer 1

我会使用累积总和和一些相对简单的比较:

select t2.*,
       (case when t2.running_value - t2.valuebefore < t1.subtracted
             then 0
             when t2.running_value < t1.subtracted
             then t2.running_value - t1.subtracted
             else t2.valuebefore
        end) as reduction,
       (case when t2.running_value < t1.subtracted then 0
             else t2.running_value - t1.subtracted
        end) as ValueAfter
from (select t2.*,
             sum(valuebefore) over (partition by groupid order by id) as running_value
      from t2
     ) t2 join
     t1
     on t2.groupid = t1.groupid;