Calculate Profit Based on First-In, First-Out Pricing

Question

Say I have purchase and sales data for some SKUs:

po_id | sku | purchase_date    | price | qty
----------------------------------------------
    1 | 123 | 2013-         


        

Answer 1

setting ambient

    declare @purchased table (id int,sku int,dt date,price money,qty int)
    declare @sold table (id int,sku int,dt date,price money,qty int)

    insert into @purchased
    values( 1 , 123 , '2013-01-01 12:25' , 20.15 ,   5)
        ,(2 , 123 , '2013-05-01 15:45' , 17.50 ,   3)
        ,(3 , 123 , '2013-05-02 12:00' , 15.00 ,   1)
        ,(4 , 456 , '2013-06-10 16:00' , 60.00 ,   7)

    insert into @sold
    values(1 , 123 , '2013-01-15 11:00' , 30.00 ,   1)
          ,(2 , 123 , '2013-01-20 14:00' , 28.00 ,   3)
          ,(3 , 123 , '2013-05-10 15:00' , 25.00 ,   2)
          ,(4 , 456 , '2013-06-11 12:00' , 80.00 ,   1)

a sqlserver solution should be...

    with cte_sold as (select sku,sum(qty) as qty, SUM(qty*price) as total_value
                      from @sold
                      group by sku
                      )
    ,cte_purchased as (select id,sku,price,qty 
                       from @purchased
                       union all select id,sku,price,qty-1 as qty 
                       from cte_purchased
                       where qty>1
                    )
    ,cte_purchased_ordened as(select ROW_NUMBER() over (partition by sku order by id,qty) as buy_order
                                    ,sku
                                    ,price
                                    ,1 as qty
                              from cte_purchased 
    )

    select P.sku
          ,S.total_value - SUM(case when P.buy_order <= S.qty then P.price else 0 end) as margin
    from cte_purchased_ordened P
    left outer join cte_sold S
    on S.sku = P.sku
    group by P.sku,S.total_value,S.qty

resultset achieved

    sku margin
    123 45,75
    456 20,00

same result for sku 123 example in the problem description...

30*1 + 28*3 + 25*2 - 20.15*5 - 17.50*1 = 45.75