动态生成树

string strSQL = "";
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            if (Session["MemberID"].ToString() != "10000")
            {
                strSQL = "Select * from tTreeMain where step=3 or step=2 Order by step desc";
            }
            if (Session["Admin"].ToString() != "")
            {
                strSQL="Select * from tTreeMain where step=1 or step=2";
            }
            DataView dvMain = dv(strSQL);
            foreach (DataRowView dvRV in dvMain)
            {
                TreeNode tn = new TreeNode();
                tn.Value = dvRV["id"].ToString();
                tn.Text = dvRV["text"].ToString();
                tn.NavigateUrl = dvRV["url"].ToString();
                TreeView1.Nodes.Add(tn);
                AddchildNode(tn);
            }
           
        }
    }
    private void AddchildNode(TreeNode tn)
    {
        int id = Convert.ToInt32(tn.Value);
        DataView dvChild = dv("select * from tTree where id=" + id);
        foreach (DataRowView dvRV in dvChild)
        {
            TreeNode ctn = new TreeNode();
            ctn.Value = dvRV["pid"].ToString();
            ctn.Text = dvRV["text"].ToString();
            ctn.NavigateUrl = dvRV["url"].ToString();
            tn.ChildNodes.Add(ctn);
        }

    }
    private DataView dv(string query)
    {
        string strConn;
        SqlConnection sqlConn;
        strConn = System.Configuration.ConfigurationManager.AppSettings["ConnectString"];
        sqlConn = new SqlConnection(strConn);
        sqlConn.Open();
        SqlDataAdapter sda = new SqlDataAdapter(query, sqlConn);
        DataSet ds = new DataSet();
        sda.Fill(ds, "tTree");
        return ds.Tables["tTree"].DefaultView;
    }