More elegant solution to reporting query?

Question

I was recently asked to produce a one-time report that would identify any products that were or are currently being sold/stocked out of two different locations (821,822) at once, and where the product is currently is in stock at both. The table layout is basically like this:
Sales_Staging
Location_ID
Product_ID
Sales_Current
Sales_1ago
Sales_2ago
Sales_72ago
On_Hand_Current
On_Hand_1ago
On_Hand_62ago
(sales/OH stored horizontally on table, shifted once a week)
I wanted to produce a report of the products selling out of the two location IDs (821,822)--a list ordered by product, showing the historical sales/inventory at each location side-by-side. For example:
Location  Product  Sales_Current  Sales_1ago  ... On_Hand_Current ...
821        ABC       0                    1                   3
822        ABC       0                    1                   4
821        DEF
822        DEFTo get results turned around quickly, I used this ugly SQL below. The Sales_Staging table has millions of records, and the query plodded. I feel like I'm asking Oracle to process the same data for each location twice.
I'm working in 10gR2. For my own education and future reference, I figured I'd see if the experts had a more elegant solution? Thanks in advance.
SELECT location_id, product_id, sales..., on_hand...
  FROM Sales_Staging
WHERE location_id = 821
  AND on_hand_current > 0
  AND (sales_current + sales_1ago + sales_2ago + ... + on_hand_1ago + ...) > 0
  AND product_id in
    (SELECT product_id
        FROM Sales_Staging
      WHERE location_id = 822
         AND on_hand_current > 0
         AND (sales_current + sales_1ago + sales_2ago + ... + on_hand_1ago + ...) > 0)
UNION
SELECT location_id, product_id, sales..., on_hand...
  FROM Sales_Staging
WHERE location_id = 822
  AND on_hand_current > 0
  AND (sales_current + sales_1ago + sales_2ago + ... + on_hand_1ago + ...) > 0
  AND product_id in
      (SELECT product_id
      FROM Sales_Staging
      WHERE location_id = 821
         AND on_hand_current > 0
         AND (sales_current + sales_1ago + sales_2ago + ... + on_hand_1ago + ...) > 0)
ORDER BY product_id, location_id

Answer 1

The below query is obviously untested, but at least it shows a different approach to this problem
with subset_of_sales_staging as
( select *
    from sales_staging
   where location_id in (821,822)
     and on_hand_current > 0
     and ( sales_current + ... ) > 0
select distinct s1.*
  from subset_of_sales_staging s1
     , subset_of_sales_staging s2
where s1.product_id = s2.product_id
   and (  s1.location_id = 821 and s2.location_id = 822
       or s1.location_id = 822 and s2.locatino_id = 821
order by product_id
     , location_idChances are good that this query will operate on smaller subsets than your original query. But this depends of course on the data volumes and distributions, which I don't know.
Regards,
Rob.