private void DataGridDanhSachMonHoc_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
try
{
db = new MyDbContext();
var obj = dataGridDanhSachMonHoc.SelectedItem;
monHoc = db.MonHoc.Find((obj as MonHoc).MaMonHoc);
if (obj != null)
{
MonHoc monHoc = (MonHoc)obj;
LopDAO dao = new LopDAO();
List <Lop> lops = dao.GetLops(monHoc.MaMonHoc);
dataGridDanhSachLop.ItemsSource = lops;
}
}catch (Exception ex) { }
}