根据TreeView的结点数据的ID号，返回该结点的深度

通过递归的方式实现，函数代码如下：

        /// <summary>
        /// 根据指定目录ID号，获得该目录的层级，
        /// </summary>
        /// <param name="curID">指定目录ID号</param>
        /// <param name="dt">datatable</param>
        /// <param name="ai_level">计算层级,以0开始</param>
        public void GetNodesLevel(string curID,DataTable dt,ref int ai_level)
        {
            string curparentid = "", curIDnew = "";
            DataView dv = dt.DefaultView;

            dv.RowFilter = "ID = " + System.Convert.ToDecimal(curID) + "";
            dv.RowStateFilter = DataViewRowState.OriginalRows;
            if (dv.Count > 0)
            {
                curparentid = dv[0]["PARENTID"].ToString().Trim();
                dv.RowFilter = "ID = " + System.Convert.ToDecimal(curparentid) + "";
                dv.RowStateFilter = DataViewRowState.OriginalRows;
                if (dv.Count > 0)
                {
                    curIDnew = dv[0]["ID"].ToString().Trim();
                    ai_level++;
                    GetNodesLevel(curIDnew, dt, ref ai_level);
                }
            }
        }

在aspx.cs中如下：

                int li_i = 0;
                GetNodesLevel("2", ds.Tables[0], ref li_i);
                ClientScript.RegisterClientScriptBlock(this.GetType(), "", "<script>alert('"+li_i.ToString()+"')</script>");