//pattern factory method
private void Button_to_group(object sender, RoutedEventArgs e)
{
Groupa groupa = new Groupa();
var g = groupa.CreateNew(first.Text, second.Text, third.Text, four.Text);
g.AddToDataBase();
}
public override Table CreateNew(String first, String second, String third, String four)
{
Groupa g = new Groupa();
g.group = new group();
g.group.id_gr = Convert.ToInt32(first);
g.group.group_name = second;
g.group.st_counts = Convert.ToInt32(third);
g.group.id_fl = Convert.ToInt32(four);
return(g);
}