private static void DisplayCategories()
        {
            using (var db = new ProdContext())
            {
                var query = from cat in db.Categories
                            orderby cat.Name
                            select cat;

                /*    foreach (var c in query)
                 *  {
                 *      Console.WriteLine("Nazwa kategorii", c.Name );
                 *  }*/
            }
            Console.ReadKey();
        }