Question

I have a list of purchases by date. EG:

ItemCode, Purchase Date, Purchase Qty

• XXX, 01 Jan 2012, 10
• XXX, 10 Jan 2012, 5

For the item I have a corresponding Sales transactions:

Item, Sales Date, Sales Qty

• XXX, 02 Jan 2012, -5
• XXX, 09 Jan 2012, -3
• XXX, 11 JAN 2012, -3

I am looking to get a SQL query (Without a cursor), to get the balance on each purchase order quantity. I.e Run each purchase (First in first out) to 0. (For the purposes of aging inventory )

How can you join the Purchases to the Sales to get this balance remaining each purchased Inventory Lot? Is this possible without a cursor?

Answer 1

Yes.

You union the two tables together, and run a running total on the resulting set.

   ;with cte as 
   (
       select itemcode, purchasedate as tdate, purchaseqty as qty from purchases
       union
       select itemcode, salesdate, salesqty from sales
   )
   select 
    t1.*,
    SUM(t2.qty)
   from cte t1
    left join cte t2 
        on t1.tdate>=t2.tdate
        and t1.item = t2.item
   group by t1.item, t1.pdate, t1.qty   

To get the stock remaining at any particular time the same principal applies.

select p1.*, 
    case when (select SUM(abs(qty)) from sales) > SUM(p2.qty) then 0
    else SUM(p2.qty) - (select SUM(abs(qty)) from sales)  end as stockremaining         
    from purchases p1
    left join purchases p2 on p1.item = p2.item 
    and p2.purchasedate <= p1.purchasedate
group by p1.purchasedate, p1.item, p1.qty

gives

1   2012-01-01    10    0
1   2012-01-10     5    4