How to treat negative values when performing a sum

Question

Let's suppose i have the following table.

|item_no | po_num | line_num | recv_qty | req_qty |
|--------|--------|----------|----------|---------|
|123     | 001    | 10       | 10       | 10      | 
|234     | 001    | 20       | 25       | 30      |
|345     | 001    | 30       | 80       | 80      |
|345     | 001    | 30       | -80      | 80      |
|567     | 002    | 10       | 40       | 10      |
|789     | 002    | 20       | 55       | 30      |
|987     | 002    | 30       | -70      | 70      |

In this case, what this represents is that, for item 123 one purchase order (po_num) was created for items 123, 234 and 345. There is a different line_no for each item.

In the case of the po_num = 001 the line_num was returned to the vendor and so there are two entries with po_num = 001 and line_num = 30 one with a negative rev_qty indicating the order was returned.

There is also one case, for item 987 that there is only one entry with a negative rev_qty indicating that the order was returned.

What i need is a query that is able to give me the sum of the recv_qty and the req_qty so i can get the ratio and see if the providers are fulfilling the purchase orders properly. I need to be able of handling the two cases. I believe that in the second case it is enough if i add a "where recv_qty >=0" since i am interested in knowing if a provider did not deliver the order, not being necessarily returned. I am having creating a query that handles the two cases. Any help will be appreciated.

Answer 1

Not really sure what you are looking but here is a guess.

declare @Something table
(
    item_no int
    , po_num char(3)
    , line_num int
    , recv_qty int
    , req_qty int
)

insert @Something
values
(123, '001', 10, 10, 10)
,(234, '001', 20, 25, 30)
,(345, '001', 30, 80, 80)
,(345, '001', 30, -80, 80)
,(567, '002', 10, 40, 10)
,(789, '002', 20, 55, 30)
,(987, '002', 30, -70, 70)

select item_no
    , po_num
    , sum(case when recv_qty > 0 then recv_qty else 0 end) as QuantitySold
    , sum(case when recv_qty < 0 then ABS(recv_qty) else 0 end) as QuantityReturned
from @Something
group by item_no
    , po_num