private void btnUpdate_Click(object sender, RoutedEventArgs e)
{
SqlDB.Update(txtID.Text, txtVorname.Text, txtNachname.Text, txtStrasse.Text, txtPLZ.Text, txtOrt.Text);
DTGrid.ItemsSource = null;
DTGrid.ItemsSource = SqlDB.LoadData().DefaultView;
}
private void btnAdd_Click(object sender, RoutedEventArgs e)
{
SqlDB.AddData(txtVorname.Text, txtNachname.Text, txtStrasse.Text, txtPLZ.Text, txtOrt.Text);
}