public string DataTableToXMLString(System.Data.DataTable dt)
    {
        if (dt == null) return null;
        System.Text.StringBuilder sXML = new System.Text.StringBuilder();
        System.IO.StringWriter sWriter = new System.IO.StringWriter(sXML);
        System.Xml.XmlTextWriter xWriter = new System.Xml.XmlTextWriter(sWriter);

        if (string.IsNullOrEmpty(dt.TableName)) dt.TableName = "row";
        try
        {
            dt.WriteXml(xWriter);
            return sXML.ToString();
        }
        catch { }
        finally { sWriter.Close(); xWriter.Close(); }
        return null;
    }
 protected void Page_Load(object sender, EventArgs e)
{
string v1=Request.Form["v1"],v2=Request.Form["v2"];
if (string.IsNullOrEmpty(v1)&&string.IsNullOrEmpty(v2)){
DataTable dt;
//通过v1，v2读取数据库填充DataTable
string xml=DataTableToXMLString(dt);/////
Response.ContentType = "text/xml";//////////
Response.Write(xml);///////
Response.End();///////
}
}