public void Delete_Marque(String MarqueName, List <String> MarqueNames) { if (MarquesDao.FindMarqueByMarqueName(MarqueName)) { MarquesDao.DeleteMarque(MarquesDao.FindMarquesByMarqueName(MarqueName)); MarqueNames.Remove(MarqueName); if (!MarquesDao.FindMarqueByMarqueName(MarqueName)) { MessageBox.Show("Delete succeed!"); } } else { MessageBox.Show("Marque doesn't exist!"); } }