SQL Update Table with Sum Results

Question

I have two Tables ("Shortages", "Orders"). Shortages contains each Material once, Orders is all the Material orders. I am trying to update Shortages field CurrentWeek with the sum of all orders of a material from Orders.

I am not an SQL guru and this is stumping me. I have googled things but I can't seem to get anything to work.

I can write a select query that gets me what I want with all the WHERE clauses but I can't get the values into the other table.

Any help is greatly appreciated!

Answer 1

It sounds like you want something like this:

UPDATE Shortages
   SET CurrentWeek = (SELECT SUM(quantity)
                        FROM Orders
                       WHERE Orders.Material = Shortages.Material
                         AND <which records in Orders count toward the current Shortages record>)
 WHERE <which records in Shortages you want to update>

Obviously you'll need to modify it with the proper column names.

Answer 2

Get the SUM() first and then perform an update join. Something like below (** It's a demo query but hope you understood the point)

update Shortages s
join (
select orderid, sum(order_qty) as total_qty
from orders
group by orderid ) xxx on s.orderid = xxx.orderid
set s.CurrentWeek = xxx.total_qty;