将数组添加到我的 ExecuteReader() 函数

Question

我正在尝试从我在 MYSQL 中创建的数据库中获取数据。我相信我的代码中的 DML 是正确的。我在另一个线程上看到我需要使用数组，这样我就可以从我的 table 中获取所有行，但我正在努力研究如何将它们包含在我的代码中：

string cs = "server...";

MySqlConnection connection = new MySqlConnection(cs);


try
{
    Console.WriteLine("Connection sur MySQL...");
    connection.Open();
 
    string Insertion ="insert into Passager(...)values(...)";
    string Insert2 = "insert into Reservation(...)values(...)";
    string req1 = "SELECT CodePassager,";
    string req2 = "SELECT CodePassager,...";
    string req3 = "SELECT CodePassager,...";
    string joint = "SELECT Reservation...";

    MySqlCommand NQuery = new MySqlCommand(Insertion, connection);
    MySqlCommand NQuery2 = new MySqlCommand(Insert2, connection);
    MySqlCommand requete1 = new MySqlCommand(req1, connection);
    MySqlCommand requete2 = new MySqlCommand(req2, connection);
    MySqlCommand requete3 = new MySqlCommand(req3, connection);
    MySqlCommand reqjoint = new MySqlCommand(joint, connection);

    NQuery.ExecuteNonQuery();
    NQuery2.ExecuteNonQuery();

    //1st request
    using (MySqlDataReader reader1 = requete1.ExecuteReader())
    {
        reader1.Read();
        int CodePassager;
        string Nom, Prenom;
        CodePassager = (int)reader1[0];
        Nom = (string)reader1[1];
        Prenom = (string)reader1[2];
        Console.WriteLine("code: {0},nom:{1},prenom:{2}", CodePassager, Nom, Prenom);
        reader1.Close();
    }

    //2nd request
    using (MySqlDataReader reader2 = requete2.ExecuteReader())
    {
        reader2.Read();
        int CodePassager;
        string Nom, Prenom, Adresse;
        CodePassager = (int)reader2[0];
        Nom = (string)reader2[1];
        Prenom = (string)reader2[2];
        Adresse = (string)reader2[3];
        Console.WriteLine("code:{0},...);
        reader2.Close();
    }

    //3rd request
    using (MySqlDataReader reader3 = requete3.ExecuteReader())
    {
        reader3.Read();
        int CodePassager;
        string Nom, Prenom, Adresse;
        CodePassager = (int)reader3[0];
        Nom = (string)reader3[1];
        Prenom = (string)reader3[2];
        Adresse = (string)reader3[3];
        Console.WriteLine("code: {0}...);
        Console.WriteLine("---------------------------------------------------");
        Console.WriteLine("Reservation(s) pour ce client:");
        Console.WriteLine("---------------------------------------------------");

        reader3.Close();
        //request to show every reservation per passenger
        using (MySqlDataReader reader4 = reqjoint.ExecuteReader())
        {
            reader4.Read();
            int CodeReservation;
            string StatutReservation, DateReservation;
            CodeReservation = (int)reader4[0];
            StatutReservation = (string)reader4[1];
            DateReservation = (string)reader4[2];
            Console.WriteLine("code reservation:{0}...);
            reader4.Close();
        }
    }


}

catch (Exception e)
{
    Console.WriteLine(e.Message);
}
finally
{
   
    connection.Close();
}

使用我当前的代码，每个请求只能得到一个结果，但我需要所有数据。

（抱歉，英语不是我的母语。）

Answer 1

如上所述，答案在 MySqlDataReader 的示例部分，但代码写得不是很好。更好的版本应该清楚如何从 select 查询中读取多个值：

public void ReadMyData(string myConnString) {
    string mySelectQuery = "SELECT OrderID, CustomerID FROM Orders";

    using(MySqlConnection myConnection = new MySqlConnection(myConnString))
    using(MySqlCommand myCommand = new MySqlCommand(mySelectQuery,myConnection))
    {   
        myConnection.Open();

        using(MySqlDataReader myReader = myCommand.ExecuteReader())
        {
            // Always call Read before accessing data.
            while (myReader.Read()) {
                Console.WriteLine(myReader.GetInt32(0) + ", " + myReader.GetString(1));
            }

            // always call Close when done reading.
            myReader.Close();
        }

        // Close the connection when done with it.
        myConnection.Close();
    }
}

许多类型都是一次性的，因此它们可以与 using 部分一起使用。此外，MySqlConnection.Close 方法表明它是关闭连接的首选方式，因此应该手动关闭它而不是依赖于处置。尽管文档没有说明任何内容，但我对 MySqlDataReader.Close 的假设相同。

Answer 2

感谢所有回答的人，我发现了我的错误，直到你指出它我才完全理解 while() 并且我修复了它除了最后一个 while 需要我有一个 while 循环在一个开放的 reader（第 3 个和第 4 个请求）中，我只找到 this and this，我不确定我是否走对了路。这就是我修复答案的方式：

        //1st request
        using (MySqlDataReader reader1 = requete1.ExecuteReader())
        {
            while (reader1.Read())
            {
                int CodePassager;
                string Nom, Prenom;
                CodePassager = (int)reader1[0];
                Nom = (string)reader1[1];
                Prenom = (string)reader1[2];

                Console.WriteLine("code: {0}...");
            }
            reader1.Close();
        }

        //2nd request
        using (MySqlDataReader reader2 = requete2.ExecuteReader())
        {
            while (reader2.Read())
            {
                int CodePassager;
                string Nom, Prenom, Adresse;
                CodePassager = (int)reader2[0];
                Nom = (string)reader2[1];
                Prenom = (string)reader2[2];
                Adresse = (string)reader2[3];
                Console.WriteLine("code: {0}...");
            }
            reader2.Close();
        }

        //3rd request
        using (MySqlDataReader reader3 = requete3.ExecuteReader())
        {
            while (reader3.Read())
            {
                int CodePassager;
                string Nom, Prenom, Adresse;
                CodePassager = (int)reader3[0];
                Nom = (string)reader3[1];
                Prenom = (string)reader3[2];
                Adresse = (string)reader3[3];
                Console.WriteLine("code: {0}...");
                reader3.Close();
                using (MySqlDataReader reader4 = reqjoint.ExecuteReader())
                {
                    while (reader4.Read())
                    {
                        int CodeReservation;
                        string StatutReservation, DateReservation;
                        CodeReservation = (int)reader4[0];
                        StatutReservation = (string)reader4[1];
                        DateReservation = (string)reader4[2];
                        Console.WriteLine("code...");
                    }
                    reader4.Close();
                }
            }
        }
    }
    catch (Exception e)
    {
        Console.WriteLine(e.Message);
    }
    finally
    {

        connection.Close();
    }
}

}

将数组添加到我的 ExecuteReader() 函数

Add arrays to my ExecuteReader() function

.net

c#

mysql

ado.net