DELETE c2 
  FROM av_url_alias c2 
   JOIN 
   (SELECT query, MAX(url_alias_id) AS maxid 
     FROM `av_url_alias` c1
     GROUP BY query
     HAVING  COUNT(*) > 1
    ) AS lim
      ON (c2.query) = (lim.query) AND c2.url_alias_id < maxid;

delete from t using av_url_alias t, av_url_alias t2 where t.url_alias_id > t2.url_alias_id and t.query = t2.query;