protected void Page_Load(object sender, EventArgs e)
 {
     if (!Page.IsPostBack)
     {
         ArrayList residentList = EIDdbResidentManagement.RetrieveResidentNoName();
         dlResident.DataSource = residentList;
         dlResident.DataBind();
     }
 }
        protected void dlResident_ItemCommand(object source, DataListCommandEventArgs e)
        {
            if (e.CommandName == "Del")                              //Button里的CommandName
            {
                int ID = (int)dlResident.DataKeys[e.Item.ItemIndex]; //获取删除信息的ID
                EIDdbResidentManagement.DeleteByID(ID);
            }
            ArrayList residentList = EIDdbResidentManagement.RetrieveResidentNoName();

            dlResident.DataSource = residentList;
            dlResident.DataBind();
        }