$list = ORM::factory('Event');
if(!empty($from)){
    $list->where('event_end', '>=', $from);
}
if(!empty($to)){
    $list->where('event_end', '<=', $to);
}
$list->where('pages_num', '>', 0)
->order_by('event_end', 'DESC')
->find_all();

$list = ORM::factory('Event')
->where('event_end', '>=', $from)
->where('event_end', '<=', $to)
->where('pages_num', '>', 0)
->order_by('event_end', 'DESC')
->find_all();