Question

I need to select statements where is fixed post id, group by user id and with latest date. Here is what i have:

$bids = "SELECT uid, Max(date_made), bid FROM ".$wpdb->prefix."auction_bids WHERE pid=$pid GROUP BY uid";

In this query is problem only with date, it returns first results, but i need last.
Here is the screen of my database:

Answer 1

You need to obtain the groupwise maximum:

SELECT uid, date_made, bid
FROM   ${wpdb->prefix}auction_bids NATURAL JOIN (
  SELECT   uid, MAX(date_made) AS date_made
  FROM     ${wpdb->prefix}auction_bids
  WHERE    pid = $pid
  GROUP BY uid
) AS t
WHERE  pid = $pid

See it on sqlfiddle.