Ошибка в коде вывода данных из MySQL таблицы

MySqlCommand command = new MySqlCommand(); ;
            string connectionString, commandString;
            connectionString = "Database=" + WIT_DB + ";Data Source=" + WIT_IP + ";User Id=" + WIT_ID + ";Password=" + WIT_Password + ";charset=utf8";
            MySqlConnection connection = new MySqlConnection(connectionString);
            commandString = "SELECT * FROM iqaou;";
            command.CommandText = commandString;
            command.Connection = connection;
            MySqlDataReader reader;
            try
            {
                command.Connection.Open();
                reader = command.ExecuteReader();
                while (reader.Read())
                {
                    string a = Convert.ToString(reader.GetValue(0));
                    MessageBox.Show(a);
                }
                reader.Close();
            }
            catch (MySqlException ex)
            {
                Console.WriteLine("Error: \r\n{0}", ex.ToString());
            }
            finally
            {
                command.Connection.Close();
            }

string mass = "1";
                MySqlCommand command = new MySqlCommand(); ;
                string connectionString, commandString;
                connectionString = "Database=" + WIT_DB + ";Data Source=" + WIT_IP + ";User Id=" + WIT_ID + ";Password=" + WIT_Password + ";charset=utf8";
                MySqlConnection connection = new MySqlConnection(connectionString);
                commandString = "SELECT uri * FROM iqaou where id='"+mass+"'+'";
                command.CommandText = commandString;
                command.Connection = connection;
                MySqlDataReader reader;
                try
                {
                    command.Connection.Open();
                    reader = command.ExecuteReader();
                    while (reader.Read())
                    {
                        string a = Convert.ToString(reader.GetValue(0));
                        MessageBox.Show(a);
                    }
                    reader.Close();
                }
                catch (MySqlException ex)
                {
                    Console.WriteLine("Error: \r\n{0}", ex.ToString());
                }
                finally
                {
                    command.Connection.Close();
                }

//поля класса
string  connectionString = @"Database=WIT_DB;Data Source=WIT_IP;User 
Id=WIT_ID;Password=WIT_Password;charset=utf8";
string commandString =  "SELECT uri FROM iqaou where id=@id";
string commandUpdate =  "Update iqaou Set uri=@uri where id=@id";
//....
//метод получения данных
int IdRow=1;
try
{
  string newData;
  using( MySqlConnection connection = new MySqlConnection(connectionString)
  {
     connection.Open();
     using(MySqlCommand command = new MySqlCommand(commandString, connection))
     {                
         command.Parameters.AddWithValue("@id", IdRow);
         Console.WriteLine(command.ExecuteScalar());
         Console.WriteLine("введите новое значение");
          newData = Console.ReadLine();
     }
     using(MySqlCommand command = new MySqlCommand(commandUpdate, connection))
     {     
         command.Parameters.AddWithValue("@id", IdRow);
         command.Parameters.AddWithValue("@uri", newData);
         command.ExecuteNonQuery();
     }
  }
}
catch (MySqlException ex)
{
   Console.WriteLine("Error: \r\n{0}", ex.ToString());
}

 using( MySqlConnection connection = new MySqlConnection(connectionString)  )

            string connectionString = @"Database=" + WIT_DB + ";Data Source=" + WIT_IP + ";User Id=" + WIT_ID + ";Password=" + WIT_Password + ";charset=utf8"; ;
string commandString =  "SELECT uri FROM iqaou where id=@id";
string commandUpdate =  "Update iqaou Set uri=@uri where id=@id";
//....
//метод получения данных
int IdRow=1;
try
{
  string newData;
  using( MySqlConnection connection = new MySqlConnection(connectionString))
  {
     connection.Open();
     using(MySqlCommand command = new MySqlCommand(commandString, connection))
     {                
         command.Parameters.AddWithValue("@id", IdRow);
         MessageBox.Show(Convert.ToString(command.ExecuteScalar()));
         MessageBox.Show("введите новое значение");
         newData = Convert.ToString("1");
     }
     using(MySqlCommand command = new MySqlCommand(commandUpdate, connection))
     {     
         command.Parameters.AddWithValue("@id", IdRow);
         command.Parameters.AddWithValue("@uri", newData);
         command.ExecuteNonQuery();
     }
  }
}
catch (MySqlException ex)
{
   MessageBox.Show("Error: \r\n{0}", ex.ToString());
}

MySqlConnectionStringBuilder myCSB = new MySqlConnectionStringBuilder(); 
  //myCSB.Port = 3306; 
  myCSB.Host = WIT_IP; //"localhost"
  myCSB.Password = WIT_Password;  //....
  myCSB.UserId = WIT_ID; 
  myCSB.Direct = true; 
  myCSB.Compress = true; 
  myCSB.Database = WIT_DB; 
  myCSB.MaxPoolSize = 50;
  using( MySqlConnection connection = new MySqlConnection(myCSB.ConnectionString))
  { 
       //...