C# database

private static void ReadOrderData(string connectionString) 
  { 
      string queryString = 
          "SELECT OrderID, CustomerID FROM dbo.Orders;"; 
   
      using (SqlConnection connection = 
                 new SqlConnection(connectionString)) 
      { 
          SqlCommand command = 
              new SqlCommand(queryString, connection); 
          connection.Open(); 
   
          SqlDataReader reader = command.ExecuteReader(); 
   
          // Call Read before accessing data. 
          while (reader.Read()) 
          { 
              Console.WriteLine(String.Format("{0}, {1}", 
                  reader[0], reader[1])); 
          } 
   
          // Call Close when done reading. 
          reader.Close(); 
      } 
  }