Question

I have a PriceComparison table with (StoreNumber, ItemNumber, Price) that keeps pricing data for head-to-head comparison shopping. The goal is a recordset with the following things for all stores:

• StoreNumber
• COUNT of head-to-head wins for that store
• COUNT of head-to-head losses for that store
• COUNT of head-to-head ties for that store
• SUM of all item pricing for that store
• SUM of all head-to-head competitor pricing for items above for that store

Example:

StoreNumber  ItemNumber  Price
-----------  ----------  -----
101          1           1.39
102          1           1.89
101          2           3.49
103          2           2.99
101          3           9.99
104          3           9.99

I’m thinking I can calculate these SUMs and COUNTs if I can get a temporary column added for CompetitorPrice. That way, the item has both prices listed, and it becomes easy.

How can I get this information in the correct configuration? I tried an INNER JOIN to the same table, but that gets tricky.

Thanks!

UPDATE: This is for MS SQL Server.
UPDATE: There will only be two prices per item, no more than 2 stores.

Answer 1

SELECT 
    a.storenumber,
    SUM(CASE WHEN a.price < b.price THEN 1 ELSE 0 END) AS wins,
    SUM(CASE WHEN a.price > b.price THEN 1 ELSE 0 END) AS losses,
    SUM(CASE WHEN a.price = b.price THEN 1 ELSE 0 END) AS ties,
    SUM(a.price) AS store_price_sum,
    SUM(b.price) AS competitor_price_sum
FROM
    pricecomparison a
INNER JOIN
    pricecomparison b ON 
        a.itemnumber = b.itemnumber AND 
        a.storenumber <> b.storenumber
GROUP BY
    a.storenumber