private void button2_Click(object sender, EventArgs e)
        {
            string message = "";
            int    userid  = controller.GetUser(login_box.Text, passw_box.Text);

            if (userid == -1)
            {
                message = controller.error;
                MessageBox.Show(message);
            }
            else
            {
                if (!controller.LoadUserData(userid))
                {
                    message = controller.error;
                    MessageBox.Show(message);
                }
                else
                {
                    controller.LoadUserData(userid);
                    DayFluctuation day_form = new DayFluctuation(ref controller);
                    day_form.Show();
                }
            }
            passw_box.Text = "";
            controller.Reset();
        }
        private void day_stats_win_button_Click(object sender, EventArgs e)
        {
            DayFluctuation day_form = new DayFluctuation(ref controller);

            day_form.Show();
        }