Private Sub ReadGetOrdinal(ByVal connectionString As String)
    Dim queryString As String = _
       "SELECT DISTINCT CustomerID FROM dbo.Orders;"

    Using connection As New SqlConnection(connectionString)
        Dim command As New SqlCommand(queryString, connection)
        connection.Open()

        Dim reader As SqlDataReader = command.ExecuteReader()

        ' Call GetOrdinal and assign value to variable.
        Dim customerID As Integer = reader.GetOrdinal("CustomerID")

        ' Use variable with GetString inside of loop.
        While reader.Read()
            Console.WriteLine("CustomerID={0}", reader.GetString(customerID))
        End While

        ' Call Close when done reading.
        reader.Close()
    End Using
End Sub

private static void ReadGetOrdinal(string connectionString)
{
    string queryString = "SELECT DISTINCT CustomerID FROM dbo.Orders;";
    using (SqlConnection connection =
               new SqlConnection(connectionString))
    {
        SqlCommand command =
            new SqlCommand(queryString, connection);
        connection.Open();

        SqlDataReader reader = command.ExecuteReader();

        // Call GetOrdinal and assign value to variable.
        int customerID = reader.GetOrdinal("CustomerID");

        // Use variable with GetString inside of loop.
        while (reader.Read())
        {
            Console.WriteLine("CustomerID={0}", reader.GetString(customerID));
        }

        // Call Close when done reading.
        reader.Close();
    }
}