问题
I have a table like this:
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..
What I want to achieve is to get a remaining_stock column that looks like this:
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
回答1:
Small matter using the window function Sum() over
Example
Select *
,Remaining_Stock = intial_stock - sum(Order_Quantity) over (Partition By Item Order by Line)
from YourTable
Returns
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
来源：https://stackoverflow.com/questions/48216733/sql-server-2016-calculating-remaining-stock-quantity