C# read data from oledb c# - Net-Raft.com

using System;
using System.Windows.Forms;
using System.Data.OleDb;

namespace WindowsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
string connetionString = null;
OleDbConnection cnn ;
OleDbCommand cmd ;
string sql = null;
OleDbDataReader reader ;

connetionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Your mdb filename;";
sql = "Select * from customers";

cnn = new OleDbConnection(connetionString);
try
{
cnn.Open();
cmd = new OleDbCommand(sql, cnn);
reader = cmd.ExecuteReader();
while (reader.Read())
{
MessageBox.Show(reader.GetValue(0) + " - " + reader.GetValue(1) + " - " + reader.GetValue(2) + " - " + reader.GetValue(3));
}
reader.Close();
cmd.Dispose();
cnn.Close();
}
catch (Exception ex)
{
MessageBox.Show("The connection is refused!");
}
}
}
}