private void LoginButton_Click(object sender, RoutedEventArgs e)
        {

            string connectionString = "Server=localhost;Database=edtest;Uid=root;Password=; ";

            using (MySqlConnection db_connect = new MySqlConnection(connectionString))
            {
                try
                {
                    db_connect.Open();


                    MySqlCommand command = db_connect.CreateCommand();
                    command.CommandType = CommandType.Text;
                    command.CommandText = "select * from accounts where username='" + UsernameTextbox.Text + "' and userpass='" + PasswordBox.Password + "'";
                    command.ExecuteNonQuery();
                    DataTable dt = new DataTable();
                    MySqlDataAdapter da = new MySqlDataAdapter(command);
                    da.Fill(dt);
                    int i = Convert.ToInt32(dt.Rows.Count.ToString());

                    if (i == 0)
                    {
                        MessageBox.Show("Faild to login, please try again");
                    }
                    else
                    {
                        this.Hide();
                        MainWindowLogged nw = new MainWindowLogged();
                        nw.Show();
                    }
                }
                catch (Exception ex)
                {

                    MessageBox.Show(ex.Message);
                }
            }

        }