private void cbb_NamHoc_SelectionChanged(object sender, SelectionChangedEventArgs e) { ComboBox comboBox = sender as ComboBox; if (comboBox.Name == cbb_NamHoc.Name || comboBox.Name == cbb_KhoiLop.Name) { if (cbb_NamHoc.SelectedIndex != -1 && cbb_KhoiLop.SelectedIndex != -1) { cbb_LopHoc.ItemsSource = vM_DiemCaNhan.LocDanhSach_TenLop(cbb_NamHoc.SelectedValue.ToString(), cbb_KhoiLop.SelectedValue.ToString()); } } if (comboBox.Name == cbb_NamHoc.Name || comboBox.Name == cbb_LopHoc.Name) { if (cbb_NamHoc.SelectedIndex != -1 && cbb_LopHoc.SelectedIndex != -1) { cbb_HocSinh.ItemsSource = vM_DiemCaNhan.DanhSach_HocSinh(cbb_NamHoc.SelectedValue.ToString(), cbb_KhoiLop.SelectedValue.ToString(), cbb_LopHoc.SelectedValue.ToString()); } } }