Comment se connecter à une base de donnée hébergée ?

namespace WindowsFormsApplication1
{
    static class Program
    {
        /// <summary>
        /// Point d'entrée principal de l'application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            string connectionString = null;
            try
            {
                connectionString = ConfigurationManager.ConnectionStrings["db_gsb"].ConnectionString;
                MessageBox.Show("configuration réussie");
                using (MySqlConnection connexion = new MySqlConnection(connectionString))
                {
                    connexion.Open();
                    //MySqlCommand sqlCommand = new MySqlCommand("select * from administrateur;", connexion);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }

            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }
    }
}

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <connectionStrings>
    <add name="db_gsb" connectionString="Server=_______;port=_____;Database=____;Uid=____;password=______;" />
  </connectionStrings>
</configuration>

namespace WindowsFormsApplication1 
{
    public partial class Form1 : Form 
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            mdptxt.Clear();
            logintxt.Clear();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            if ( conn(logintxt.Text, mdptxt.Text) == 1 )
            {
                MessageBox.Show("Connexion réussie");
                //ajouter lien vers l'application
            }
            else
            {
                MessageBox.Show("Mot de passe ou login incorrect !");
            }
        }

        private int conn (string user, string pass) 
        {
            user.Trim();
            pass.Trim();
            string connectionString = null;

            try
            {
                connectionString = ConfigurationManager.ConnectionStrings["db_gsb"].ConnectionString;
                
                using (MySqlConnection connexion = new MySqlConnection(connectionString))
                {
                  connexion.Open();
                    MySqlCommand sqlCommand = new MySqlCommand("select * from administrateur where username='"+user+"' and password='"+pass+"';");
                    if (sqlCommand.ExecuteScalar() == null)
                    {
                        return 0;
                    }
                    else
                    {
                        return 1;
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                return 0;
            }
        }

        private void mdpForgot_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {  
           Form2 form = new Form2();
           form.Show();
           mdpForgot.LinkVisited = true;
        }

    }
}