/**
  * 用户连接走势
  * @param int $stationid 车站id
  * @param date $sdate    起始日期
  * @param date $edate    结束日期
  */
 public function UserConnect($stationid, $sdate, $edate)
 {
     if (!$edate) {
         $where_date = " and date = '{$sdate}'";
     } else {
         $where_date = " and date BETWEEN '{$sdate}' AND '{$edate}'";
     }
     $obj = new Psys_StationRule();
     return $obj->UserConnect($stationid, $where_date);
 }