อยากสอบถามเรื่อง Datetime ใน php5 หน่อยครับ Help me plz

public function getAllSms_message() {

		$stmt = mysqli_prepare($this->connection, "SELECT * FROM $this->tablename");		
		$this->throwExceptionOnError();
		
		mysqli_stmt_execute($stmt);
		$this->throwExceptionOnError();
		
		$rows = array();
		
		mysqli_stmt_bind_result($stmt, $row->requestid, $row->requestdate, $row->callerid, $row->sender, $row->message, $row->msisdn, $row->phonestatus, $row->retry, $row->status, $row->chkstatus, $row->senttime, $row->deliverystatus);

	    while (mysqli_stmt_fetch($stmt)) {
			
	      if($row->requestdate == null)
			{
				$row->requestdate = null;
			}
			else
			{
				$row->requestdate = new DateTime($row->requestdate);		
			}
			if($row->senttime == null)
			{
				$row->senttime = null;
			}
			else
			{
				$row->senttime = new DateTime($row->senttime);
			}
			
	      $rows[] = $row;
	      $row = new stdClass();
	      mysqli_stmt_bind_result($stmt, $row->requestid, $row->requestdate, $row->callerid, $row->sender, $row->message, $row->msisdn, $row->phonestatus, $row->retry, $row->status, $row->chkstatus, $row->senttime, $row->deliverystatus);
	    }
		
		mysqli_stmt_free_result($stmt);
	    mysqli_close($this->connection);
	
	    return $rows;
	}