$q = $modx->db->query('SELECT c.id, g.filename FROM '.$modx->getFullTableName('site_content').' as c, '.$modx->getFullTableName('maxigallery').' as g
    WHERE c.id=g.gal_id AND g.pos=(select min(pos) from '.$modx->getFullTableName('maxigallery').' where c.id=gal_id AND !hide AND c.published)
    ORDER BY c.menuindex DESC');
  while( $res = $modx->db->getRow( $q, 'num' ) ){
    $ret[] = $res[0].'|'.$res[1];
  }
  echo implode( '|', $ret );