如何检查我的程序是否与C＃中的MSQL数据库连接？

Question

Hello I'm a student and I'm stuck on a part I need to check if the problem is with my connection or with my code please don't tell me if something is wrong with my code just help me in the right direction what kind of way should I use to check if my MySql database is connected? And yes I deactivated the rest of the code to check if its the code.

 private void Btnlogin_Click_1(object sender, EventArgs e)
    {
        MySqlConnection con = new MySqlConnection("Data Source=localhost; user id = root; Password =''; Database = login; SslMode=none");
        Debug.WriteLine(con);
        /* MySqlDataAdapter sda = new MySqlDataAdapter("Select Count(*) from users where id='" + Txtusername + "' and pword='" + Txtpassword + "' ", con);
        DataTable dt = new DataTable();
        sda.Fill(dt);
        if (dt.Rows[0][0].ToString() == "1")
        {

            this.Hide();

            main ss = new main();
            ss.Show();
        }
        else
        {
            MessageBox.Show("failed to login please check your username and password");

        }*/

Answer 1

Try this way:

using (MySqlConnection connection = new MySqlConnection(connectionString))
{
    try
    {
        connection.Open();
        using (MySqlCommand command = new MySqlCommand(query, connection))
        {
            command.CommandTimeout = 60 * 5;
            using (MySqlDataReader dataReader = command.ExecuteReader())
            {
                while (dataReader.Read())
                {
                    //Reading code..
                }
            }
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.ToString());
    }
}

Notes about this code:

1) Always use using statements when you have IDisposable objects

2) The connection.Open(); instruction, will try to open the connection to your DB. If it won't work, it will throw and exception which will be catched by the try...catch defined in this code

Answer 2

namespace projectname { public partial class login : Form { SqlConnection cn = new SqlConnection("connection string here");

    public login()
    {
        InitializeComponent();

    }



    private void freshrationpurchase_Load(object sender, EventArgs e)
    {

        SqlCommand cmd = new SqlCommand();
        cmd.Connection = cn;
        cn.Open();
        cmd.CommandText = "select count( *) from user where id=@";
        SqlDataReader dr;
    dr=cmd.ExecuteReader();
        cn.Close();

    }
}

}