AS3动态数据加载错误

我使用PHP MySQL和AS3根据站点编号加载动态数据。问题是，当我单击下一个网站时，它会向现有网站添加增量并显示新网站，但由于某种原因，它不会从旧网站中删除内容？

我的PHP

$dbHost = "localhost";
$dbUser = "username";
$dbPass = "password";
$dbName = "dbname";
$dbTable = "tablename";
if (isset($_GET['sn'])) {
$sn = $_GET['sn'];
}
// connecting and selecting database
@mysql_connect($dbHost, $dbUser, $dbPass) or die(mysql_error());
@mysql_select_db($dbName) or die(mysql_error());
// getting data
  $data = "";
  $datatitle = "";
  $res = mysql_query("SELECT * FROM ".$dbTable." WHERE Site_ID='$sn'") or die(mysql_error());
  while($row = mysql_fetch_object($res)) {
    $data .= strip_tags($row->Site_Description);
}
die($data);

我的AS3包代码：

package {
import flash.display.MovieClip;
import flash.events.Event;
import flash.display.Loader;
import flash.net.URLLoader;
import flash.net.URLRequest;
import flash.net.URLRequestMethod;
import flash.text.TextField;
import flash.events.IOErrorEvent;
public class App extends MovieClip {
    public static const URL:String = 'weburl/get.php';
    private var loader:URLLoader;
    private var request:URLRequest;
    public function App():void {
        output(" ");
        loadData();
    }
    var siteNumber = 2;     
    public function loadData():void {
        var randomParam:String = "?p=" + Math.floor(Math.random() * (10000000)) + "&sn=";
        this.loader = new URLLoader();
        request = new URLRequest(URL + randomParam + siteNumber);
        request.method = URLRequestMethod.POST;
        loader.addEventListener(Event.COMPLETE, onLoadData);
        loader.addEventListener(IOErrorEvent.IO_ERROR, onDataFiledToLoad);
        loader.addEventListener(IOErrorEvent.NETWORK_ERROR, onDataFiledToLoad);
        loader.addEventListener(IOErrorEvent.VERIFY_ERROR, onDataFiledToLoad);
        loader.addEventListener(IOErrorEvent.DISK_ERROR, onDataFiledToLoad);
        loader.load(request);
        } 
    public function onLoadData(e:Event):void {
        output( e.target.data);
    }
    private function onDataFiledToLoad(e:IOErrorEvent):void {
        output("onDataFiledToLoad error=" + e.text);
    }
    public function output(str:String):void {
        var text:String = field.htmlText;
        field.htmlText = str + text;
    }
    function removeExisting():void {
            this.loader.close();
    }
  }

}

我在帧上使用的代码

next_site1.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandlernext_site1); 
            function mouseDownHandlernext_site1(event:MouseEvent):void 
            { siteNumber = siteNumber + 1;
                SiteNumberText1.text = siteNumber.toString();
                loadData();
            }
prev_site1.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandlerprev_site1); 
            function mouseDownHandlerprev_site1(event:MouseEvent):void 
            { siteNumber = siteNumber - 1;
                SiteNumberText1.text = siteNumber.toString();
                loadData();
            }

我知道你必须卸载数据，但似乎找不到有效的解决方案。

我看了下面的这些问题，但它们确实有帮助（没有提到如何卸载数据，也没有提到为什么新数据没有取代旧数据。）：

xml数据到动态文本AS3 flash

AS3保存&将多个文本框数据加载到本地文件