asp.net 操作xml

asp.net 对xml文件的读写,添加,修改,删除操作
下面有代码调试正确
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Xml;
private XmlDocument xmlDoc;
        //load xml file
        private void LoadXml()
        {
            xmlDoc=new XmlDocument();
            xmlDoc.Load(Server.MapPath("User.xml"));
        }
        //添加节点
        private void AddElement()
        {
            
            LoadXml();
            XmlNode xmldocSelect=xmlDoc.SelectSingleNode("user");
            
            XmlElement el=xmlDoc.CreateElement("person"); //添加person节点
            el.SetAttribute("name","风云"); //添加person节点的属性"name"
            el.SetAttribute("sex","女");   //添加person节点的属性 "sex"
            el.SetAttribute("ag