SQL Running Subtraction

Question

I have a result set as below:

Item    ExpectedQty  ReceivedQty  Short
Item01  30           45           5
Item01  20           45           5

Item02  40             


        

Answer 1

select a.Item, a.ExpectedQty,b.ReceivedQty, (a.ExpectedQty - b.ReceivedQty) as 'Short' from a join b on a.Item = b.Item