private void InitTree(TreeNodeCollection Nds, string parentId)

    {

        TreeNode tmpNd;

        IList<ProClass> rows = ProClassService.SelectParent(int.Parse(parentId));

        foreach (ProClass row in rows)

        {

            tmpNd = new TreeNode();

            tmpNd.Value = row.ID.ToString();

            tmpNd.Text = row.Name;

            tmpNd.NavigateUrl = "Product_list.aspx?ProClassId=" + tmpNd.Value;

            Nds.Add(tmpNd);

            if (row.IsLeaf != "1")

                InitTree(tmpNd.ChildNodes, tmpNd.Value);

        }

    }