PHP pass by Reference พอหลุด จาก function แล้วค่าไม่ออกค่ะ รบกวนด้วยนะคะ

  function show_user_dt($user_id,&$data){
    $strUserQry =  "SELECT * FROM `user` WHERE `user_id` = " .$user_id;
	$objQuery = mysql_query($strUserQry) or die ("Error Query [".$strUserQry."]");
	
	while($objResult = mysql_fetch_array($objQuery))	{
		$data = array ( "0"=>$objResult["user_username"], 
		                "1"=>$objResult["user_password"]);
   		//$data[0] = $objResult["user_username"];
   		//$data[1] = $objResult["user_password"];		
   }
      echo "in while-------------username   ".$data[0];
      echo "in while-------------pw   ".$data[1];
return $data;
  }

   show_user_dt($user_id);
   echo "<br>   ".$data;
   
     echo " <br>Out of while loop -------------username   ".$data["0"];
     echo "<br>-------------pw   ".$data["1"];