dropdownlist求无限级树形不使用手动绑定数据

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DataTable datatable = this.GetDataTable();
            DataRow[] row = datatable.Select("ParentID=-1");
            //添加根目录
            for (int i = 0; i <= row.Length-1; i++)
            {
                ListItem li = new ListItem(row[i]["MajName"].ToString());
                //ListItem li2 = new ListItem(row[1]["MajName"].ToString());
                DropDownList1.Items.Add(li);
                //DropDownList1.Items.Add(li2);
                addOtherDll("", Convert.ToInt32(row[i]["MajID"]), datatable, 1);
            }
        }
    }
    /**/
    /// <summary>
    /// 添加其他节点
    /// </summary>
    /// <param name="Pading">空格</param>
    /// <param name="DirId">父路径ID</param>
    /// <param name="datatable">返回的datatable</param>
    /// <param name="deep">树形的深度</param>
    private void addOtherDll(string Pading, int DirId, DataTable datatable, int deep)
    {
        DataRow[] rowlist = datatable.Select("ParentID='" + DirId + "'");
        foreach (DataRow row in rowlist)
        {
            string strPading = "";
            for (int j = 0; j < deep; j++)
            {
                strPading += "　";         //用全角的空格
            }
            //添加节点
            ListItem li = new ListItem(strPading + "|--" + row["MajName"].ToString());
            DropDownList1.Items.Add(li);
            //递归调用addOtherDll函数，在函数中把deep加1
            addOtherDll(strPading, Convert.ToInt32(row["MajID"]), datatable, deep + 1);
        }
    }
    /**/
    /// <summary>
    /// 从数据库中读取数据返回datatable
    /// </summary>
    /// <returns></returns>
    private DataTable GetDataTable()
    {
        SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ddltest"].ConnectionString);
        SqlDataAdapter adp = new SqlDataAdapter("select * from tblMajor", conn);
        DataSet datset = new DataSet();
        conn.Open();
        adp.Fill(datset, "tblMajor");
        return datset.Tables[0];
    }

这段是无限级树形的代码..可是我还想绑一个dropdownlist2.当dropdownlist一改变.dropodownlist就跟着改变.而且树形可以不手动绑数据吗?能直接调类文件.我是初学者希望大家帮下 --------------------编程问答-------------------- 不能用相同的datatable给两个ddl赋值

用两个datatable变量就好了

补充：.NET技术 ,  C#