在C＃中的while循环内使用IF条件。虚假值仍在循环

Question

我不知道为什么while循环中的else值仍在循环，无论结果是登录名还是无效。警报对话框始终弹出。

这些是我的代码。

MySqlConnection conn = new MySqlConnection();    

string query = "server=sample.com;port=3306;database=sample;user id=sample;password=sample";

conn.ConnectionString = query;

MySqlCommand cmd = new MySqlCommand("select * from wp_users", conn);

try

{

    conn.Open();

    MySqlDataReader myReader = cmd.ExecuteReader();

    string user1 = "";

    string pass1 = "";

    //bool stopLoop = false; // stop looping for false value;

    while (myReader.Read())

    {

        user1 = myReader[1].ToString(); //datacolumn -> user_login

        pass1 = myReader[2].ToString(); //datacolumn -> user_pass

        if ((user1 == txtUsername.Text) && (pass1 == txtPassword.Text))

        {

            Intent myIntent;

            myIntent = new Intent(Activity, typeof(index));

            string a = user1;

            myIntent.PutExtra("myItem", a);

            StartActivity(myIntent);

        }

        else

        {

            Android.Support.V7.App.AlertDialog.Builder alert = new Android.Support.V7.App.AlertDialog.Builder(Activity);

            alert.SetMessage("Invalid username or password");

            alert.SetPositiveButton("Ok", (senderAlert, args) =>

            {

                alert.Dispose();

            });

            alert.Show();

        }

    }

    myReader.Close();

}

catch (MySqlException ex)

{

    Android.Support.V7.App.AlertDialog.Builder except = new Android.Support.V7.App.AlertDialog.Builder(Activity);

    except.SetTitle("Please report this to our website(error server timeout)");

    except.SetMessage(ex.ToString());

    except.SetPositiveButton("Ok", (senderAlert, args) =>

    {

        except.Dispose();

    });

    except.Show();

}

finally

{

    conn.Close();

}