动态生成 TreeView

protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            BindTreeView(TreeView1);
        }
    }
    private void BindTreeView(TreeView treeview)
    {
        //string sql = "select * from T_ZSD where course_id="+Session["Course_id"].ToString();
        string sql = "select * from T_ZSD where course_id=13";
        DataSet ds = DbHelperSQL.Query(sql);
        DataTable dt = ds.Tables[0];
        treeview.Nodes.Clear();
        //创建根节点
        DataRow[] parentrow = dt.Select("parentid=0");
        TreeNode rootnode = new TreeNode();
        rootnode.Text = parentrow[0][2].ToString() ;
        rootnode.Value = parentrow[0][0].ToString();//主键的值
        rootnode.Expanded = true;
        rootnode.Selected = true;
        treeview.Nodes.Add(rootnode);
        CreateChildNode(rootnode,dt);
       
    }
    private void CreateChildNode(TreeNode parentNode,DataTable datatable)
    {
        DataRow[] rowlist = datatable.Select("parentid="+parentNode.Value);
        foreach (DataRow row in rowlist)
        {
            //创建新节点
            TreeNode node = new TreeNode();
            node.Value = row["PK_ZSD"].ToString();
            node.Text = row["zsd_name"].ToString();
            node.Expanded = true;
            parentNode.ChildNodes.Add(node);      
            CreateChildNode(node, datatable);         //递归调用，寻找自身的子节点   
        }
    }