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();}