Running total and calc between two column (subtraction)

Question

Hi Experts!,
I have a simple requirement but getting me frustrated :( I need to calculate stock on a series of transaction
this is my order table:
OrderNo | Item | Delivery | OrderQty
A-101 | G001 | 20110721 | 200
A-104 | G001 | 20110722 | 300
A-102 | GA02 | 20110721 | 210
and my stock table :
Item | stockQty
G001 | 300
GA02 | 0
What i want to accomplish is something like this:
OrderNo | Item | Delivery | OrderQty | StockOut
A-101 | G001 |20110721 | 200 | 200
A-104 | G001 |20110722 | 300 | 100
A-102 | GA02 |20110721 | 210 | 0
i believe there is must be a way to accomplish this, without using to create extra dummy table to store
qty of Stock out (stock-orderqty),
waiting for respons,
Thanks!

Answer 1

Try this
with order1
as
select 'A-101' orderno, 'G001' item, 20110721 delivery, 200 orderqty from dual union all
select 'A-104', 'G001', 20110722, 300 from dual union all
select 'A-105', 'G001', 20110723, 250 from dual union all
select 'A-102', 'GA02', 20110721, 210 from dual union all
select 'A-103', 'GA02', 20110721, 300 from dual
), stock
as
select 'G001' item, 600 stockqty from dual union all
select 'GA02', 500 from dual
select orderno, item, delivery, orderqty, case when qty <= stockqty then orderqty else stockqty - qty1 end stockout
  from (
         select orderno, item, delivery, orderqty, qty, nvl(lag(qty) over(partition by item order by orderno), 0) qty1, stockqty
           from (
                  select orderno, o.item, delivery, orderqty, sum(orderqty) over(partition by o.item order by orderno) qty, stockqty
                    from order1 o
                    join stock s
                      on o.item = s.item
       )Note: Tables defined in the WITH caluse are sample table to show you how the SQL works. You can just use the SELECT statement with your original table.