private void btAdd_Click(object sender, RoutedEventArgs e)
        {
            int      doctorId  = 5;
            DateTime date      = DateTime.Now.Date;
            DateTime startTime = DateTime.Now.Date;
            DateTime endTime   = DateTime.Now.Date;

            if (dpDateAddAv.Text != null)
            {
                date = Convert.ToDateTime(dpDateAddAv.Text);
            }
            if (cmbStartTime.Text != null)
            {
                startTime = Convert.ToDateTime(cmbStartTime.Text);
            }
            if (cmbEndTime.Text != null)
            {
                endTime = Convert.ToDateTime(cmbEndTime.Text);
            }
            int duration = 0;

            if (rb30M.IsChecked == true)
            {
                duration = 30;
            }
            else
            {
                duration = 60;
            }

            availability av = new availability(doctorId, date, startTime, endTime, duration);

            crud.AddAvailableTime(av);
            MessageBox.Show("Added ", av.ToString());
            dpDateAddAv.Text           = "";
            cmbStartTime.SelectedIndex = -1;
            cmbEndTime.SelectedIndex   = -1;
        }