SQL Server 2016 - 计算剩余库存数量

Question

我有一张这样的表：

正如您所看到的，我有一个名为remaining_stock的列对于每个项目的第一行是正确的，但对于后续行没有。第一行是直接的，因为您可以简单地从initial_stock中减去订单数量。

我想要的是获得一个看起来像这样的remaining_stock列：

我虽然使用row_number然后使用行号连接回同一个表..但这也不是很有用。有人能指出我正确的方向吗？

select 1 as line, 123 as item, 5 as order_quantity,10 as intial_stock
union all
select 2 as line, 123 as item, 3 as order_quantity,10 as intial_stock
union all
select 3 as line, 123 as item, 1 as order_quantity,10 as intial_stock
union all
select 4 as line, 234 as item, 5 as order_quantity,15 as intial_stock
union all
select 5 as line, 234 as item, 3 as order_quantity,15 as intial_stock
union all
select 6 as line, 234 as item, 1 as order_quantity,15 as intial_stock

Answer 1

使用窗口函数Sum（）的小问题

示例

function BytestoSmallInt(B0, B1: Byte): SmallInt;
var
  Number: SmallInt;
  pointer : ^SmallInt;
  small: array [0 .. 1] of Byte absolute Number;
begin
  pointer := @Number;
  small[0] := B1;
  small[1] := B0;
  Result := pointer^;
end;

<强>返回

Select * 
      ,Remaining_Stock = intial_stock - sum(Order_Quantity) over (Partition By Item Order by Line)
 from YourTable