SQL Server 2016 - 计算剩余库存数量 [英] SQL Server 2016 - Calculating remaining stock quantity

问题描述

我有一张这样的桌子:

如您所见，我有一列名为 left_stock 的列对于每个项目的第一行是正确的，但对于后续行则不正确.第一行很简单，因为您可以简单地从 initial_stock 中减去订单数量..

As you can see, I have a column called remaining_stock that is correct for the first line of each item but NOT for the subsequent lines. The first line is straight forward as you can simply subtract the order-quantity from initial_stock..

我想要实现的是获得如下所示的剩余库存列:

What I want to achieve is to get a remaining_stock column that looks like this:

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

I though of using row_number and then joining back to the same table using the row numbers.. but that doesn't quite work either. can someone point me in the right direction please?

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

推荐答案

使用窗口函数 Sum() over 的小事

Small matter using the window function Sum() over

示例

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

退货

line    item    order_quantity  intial_stock    Remaining_Stock
1       123     5               10              5
2       123     3               10              2
3       123     1               10              1
4       234     5               15              10
5       234     3               15              7
6       234     1               15              6

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