DataBindings เอ่อเร่อค่ะ ควรทำยังไงดีค่ะ จะดึงข้อมูลออกมาเพื่อคำนวน

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.OleDb;

namespace WebApplication2
{
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string conSrt = "Provider=Microsoft.Jet.OleDb.4.0;" + @"Data source=D:\SamplesData-2003.mdb";

            OleDbConnection conn = new OleDbConnection(conSrt);
            conn.Open();

            string sql = "SELECT * FROM dbo_ExchangeRate";
            OleDbCommand cmd = new OleDbCommand(sql, conn);

            OleDbDataAdapter adapter = new OleDbDataAdapter(cmd);

            DataSet data = new DataSet();
            adapter.Fill(data, "Rate");

            TextBox2.DataBindings.Add("Text", data, "Rate.SrllingRate");