private void delete_btn_Click(object sender, RoutedEventArgs e)
{
MessageBoxResult result = MessageBox.Show("Are you sure you want to delete this record?",
"Confirmation", MessageBoxButton.YesNo, MessageBoxImage.Question);
if (result == MessageBoxResult.Yes)
{
var student = studDataGrid.SelectedIndex;
studVM.OnDelete(student);
}
}