如何得到与lable相对应的textbox的值？

如何在btn_click中得到textbox的值，并与待填写项是相对应，写入数据库中
 protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            this.Title = "填写动态表";
            string tn = Request.QueryString["tn"];
            string rpname = Request.QueryString["rp"];
            if (tn == "") { fun.ExecuteNonQuery(""); }
            if (rpname == "") { fun.ErrMsg("系统在获取参数时错误！"); }
            rpname = Server.UrlDecode(rpname);
            Label1.Text = "填写 <font color=red>" + rpname + " </font>表";
            string sql = " select top 1 * from " + tn + "";
            SqlDataReader rs = fun.ExecuteReader(sql);
            Table tb = new Table();
            tb.CssClass = "tb_bg";
            tb.CellPadding = 3;
            tb.CellSpacing = 1;
            tb.Style["width"] = "600px";
            TableRow tr = new TableRow();
            TableCell tc = new TableCell();
            tc.CssClass = "td_bg_w";
            Label lb = new Label();
            lb.Text = "待填写项";
            tc.Controls.Add(lb);
            tr.Controls.Add(tc);
            tc = new TableCell();
            tc.CssClass = "td_bg_w";
            lb = new Label();
            lb.Text = "填写数据";
            tc.Controls.Add(lb);
            tr.Controls.Add(tc);
            tb.Controls.Add(tr);
            Panel3.Controls.Add(tb);
            for (int i = 0; i < rs.FieldCount; i++)
            {
                if (rs.GetName(i).ToString() != "person" && rs.GetName(i).ToString() != "dept" && rs.GetName(i).ToString() != "site" && rs.GetName(i).ToString() != "state" && rs.GetName(i).ToString() != "time")
                {
                    tr = new TableRow();
                    tc = new TableCell();
                    tc.CssClass = "td_bg_w";
                    lb = new Label();
                    lb.Text = rs.GetName(i).ToString();
                    lb.ID = rs.GetName(i).ToString();
                    tc.Controls.Add(lb);
                    tr.Controls.Add(tc);
                    tb.Controls.Add(tr);
                    tc = new TableCell();
                    tc.CssClass = "td_bg_w";
                    TextBox tbx = new TextBox();
                    tbx.ID = rs.GetName(i).ToString();
                    tc.Controls.Add(tbx);
                    tr.Controls.Add(tc);
                    tb.Controls.Add(tr);
                    Panel3.Controls.Add(tb);
                }
            }
            tr = new TableRow();
            tc = new TableCell();
            tc.CssClass = "td_bg_w";
            Button btn = new Button();
            btn.Text = "提交";
            btn.OnClientClick = "return confirm('你确定提交数据吗？')";
            btn.CssClass = "btn";
            btn.CommandName = "bt";
            btn.Click += new EventHandler(btn_Click);
            tc.ColumnSpan = 2;
            tc.Controls.AddAt(0, btn);
            tc.HorizontalAlign = HorizontalAlign.Center;
            tr.Controls.Add(tc);
            tb.Controls.Add(tr);            rs.Close();
        }
    }    void btn_Click(object sender, EventArgs e)
    {
        
       
    }