void BindData()
    {
        DataSet ds = new XJBLL.xjBookType().GetList("");
        TreeView1.Nodes.Clear();
        TreeNode node = new TreeNode();
        node.Value = ds.Tables[0].Rows[0]["ID"].ToString();
        node.Text = ds.Tables[0].Rows[0]["TypeName"].ToString();
        node.Expand();
        TreeView1.Nodes.Add(node);
        BindChild(node, node.Value);
    }
    void BindChild(TreeNode node, string ParentID)
    {
        DataSet ds = new XJBLL.xjBookType().GetList(" and ParentID='" + ParentID + "' ");
        for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
        {
            TreeNode childnode = new TreeNode();
            childnode.Value = ds.Tables[0].Rows[i]["ID"].ToString();
            childnode.Text = ds.Tables[0].Rows[i]["TypeName"].ToString();
            node.ChildNodes.Add(childnode);
            BindChild(childnode, childnode.Value);
        }
    }