$res = mysql_query("SELECT SQL_CALC_FOUND_ROWS a.id, b.id, b.meta_name, b.meta_value
FROM a
LEFT OUTER JOIN (SELECT * FROM b ORDER BY b.id DESC) b ON a.id = b.meta_value
WHERE b.meta_name = '***'
GROUP BY a.id
ORDER BY a.id DESC
LIMIT 0, 20");


$res = mysql_query("SELECT FOUND_ROWS()");		
$count = mysql_result($res, 0);
var_dump($count);  // string(1) "0"

SELECT SQL_CALC_FOUND_ROWS *
  FROM offers
  LEFT OUTER JOIN (SELECT * FROM `offers_meta` ORDER BY `offers_meta`.`id` DESC) offers_meta 
  ON offers.offer_id = offers_meta.offer_id
  WHERE (offers_meta.offer_id IS NOT NULL AND offers_meta.meta_name = 'nacenka') or (offers.master = 0 or offers.master = {$_SESSION['user_id']})	
  $sort and offers.hold < $datenow and offers.status = 'on sale'
  GROUP BY offers.offer_id
  ORDER BY master DESC
  $limit