Getting a list instead of a single record.

Question

Hello Experts,
I’m trying to get a record out of a table with the highest amount of money. I’ve used the following query to get the maximum about of money sitting in the table and it gave me the results.
SELECT MAX(auction_item.item_highest_bid)
FROM `auction_item`
I also need two more fields from the same table. Item_id and seller_id. Now what happens is when I write the following SQL I get a list of records instead of a SINGLE record with the highest amount of money.
SELECT MAX(auction_item.item_highest_bid),
auction_item.item_id,
auction_item.seller_id
FROM `auction_item`
GROUP BY auction_item.item_id,
auction_item.seller_id
Can please somebody shows me what’s wrong with my query and how I can get SINGLE record instead of list.
Thanks a lot in advance.

Answer 1

There are several ways to get this information - subqueries, analytical sql. A lot of it depends on the data.
Is there a possibility that two or more records will have the same MAX(auction_item.item_highest_bid)? And if so, how is this to be handled? I'm making some assumptions about item_id and seller_id...so take with a grain of salt
As an aside...you need to read up on GROUP BY and aggregation in sql as this scenario is explained in documentation/books.
Without the benefit of a database to test this, here are a couple of ideas
SELECT MAX(auction_item.item_highest_bid),
auction_item.item_id,
auction_item.seller_id
FROM auction_item
WHERE auction_item.item_highest_bid = (SELECT MAX(i_auction_item.item_highest_bid)
FROM auction_item i_auction_item
WHERE i_auction_item.item_id = auction_item.item_id
AND i_auction_item.seller_id = auction_item.seller_id)
Or
SELECT i.item_highest_bid, i.item_id, i.seller_id
FROM (SELECT a.item_highest_bid, a.item_id, a.seller_id
FROM auction_item a
ORDER BY a.item_highest_bid DESC) i
WHERE i.rownum = 1
Or
SELECT i.item_highest_bid, i.item_id, i.seller_id
FROM (SELECT a.item_highest_bid, a.item_id, a.seller_id, ROW_NUMBER() OVER (ORDER BY a.item_highest_bid DESC) bid_rank
FROM auction_item a) i
WHERE i.bid_rank = 1