$where["_string"] = "(begin_time BETWEEN {$time_start} AND {$time_end}) OR (end_time BETWEEN {$time_start} AND {$time_end}) OR (begin_time <= {$time_end} AND end_time >= {$time_end}) OR (begin_time >0 AND end_time = 0)";
} elseif (isset($_REQUEST['time_start'])) {
$time_start = strtotime($_REQUEST['time_start']);
$where["_string"] = "end_time >= {$time_start} OR end_time = 0";
// $where["_string"] = "(begin_time BETWEEN {$time_start} AND {$time_end}) OR (end_time BETWEEN {$time_start} AND {$time_end}) OR (begin_time <= {$time_end} AND end_time >= {$time_end}) OR (begin_time >0 AND end_time = 0)";