static private string GetConnectionString()
        {
            return "Data Source=127.0.0.1;Persist Security Info=True;User ID=system;Password=oracle;Unicode=True";
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string connectionString = GetConnectionString();

            OracleConnection OraConn = new OracleConnection();

            OraConn.ConnectionString = connectionString;
            OraConn.Open();

            label1.Text = OraConn.State.ToString();

            OracleDataAdapter da = new OracleDataAdapter("SELECT * FROM CONTACTTYPE", OraConn);

            OracleCommandBuilder commandBuilder = new OracleCommandBuilder(da);

            DataTable table = new DataTable();
            table.Locale = System.Globalization.CultureInfo.InvariantCulture;

            da.Fill(table);

            dataGridView1.AutoResizeColumns(DataGridViewAutoSizeColumnsMode.AllCellsExceptHeader);

            bindingSource1.DataSource = table;

            dataGridView1.DataSource = bindingSource1;

            OraConn.Close();
        }