gridview问题！

public partial class left : System.Web.UI.Page
{
    //验证用户名及绑定Tree父类;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            if (Session["username"] == null)
            {
                Response.Write("<script language=javascript>window.top.location=\"default.aspx\";</script>");            }
            else
            {
                DataView dv = drv("select * from menuctl where parentid='0'");                foreach (DataRowView datav in dv)
                {
                    TreeNode tn = new TreeNode();                    tn.Text = datav["cname"].ToString();                    tn.Value = datav["nodeid"].ToString();                    tn.Expanded = false;                    tn.SelectAction = TreeNodeSelectAction.Expand;                    TreeView1.Nodes.Add(tn);                    addchildnode(tn);
                }
            }
        }
    }
    //绑定子类及超连接;
    private void addchildnode(TreeNode tn)
    {
        int bid = Convert.ToInt32(tn.Value);        DataView dv = drv("select * from menuctl where parentid='"+bid+"'");        foreach (DataRowView datav in dv)
        {
            TreeNode ctn = new TreeNode();            ctn.Text = datav["cname"].ToString();            ctn.Value = datav["nodeid"].ToString();            ctn.NavigateUrl = datav["url"].ToString();            ctn.Target = "rform";            tn.ChildNodes.Add(ctn);
        }
    }
    //Tree数据源;
    private DataView drv(string query)
    {
        SqlConnection pr = new SqlConnection(ConfigurationManager.ConnectionStrings["mycon"].ToString());        pr.Open();        SqlDataAdapter sda = new SqlDataAdapter(query,pr);        DataSet ds = new DataSet();        sda.Fill(ds, "tree");        pr.Close();        return ds.Tables["tree"].DefaultView;
    }
   //获取子类信息;
    protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e)
    {
        string a = TreeView1.SelectedNode.Value.ToString();        Response.Write(a);
       
    }