public static string SearchDish(int id)   //поиск названия блюда по id
        {
            SmartRestaurantEntities dbs = new SmartRestaurantEntities();
            var dish = dbs.list_of_dishes.FirstOrDefault(w => w.id_dish == id).name_dish;

            return(dish);
        }
        public static List <dynamic> SelectListDishAva()        //вывод списка доступных блюд
        {
            SmartRestaurantEntities dbs = new SmartRestaurantEntities();
            var avaList = (from p in dbs.list_of_dishes
                           join m in dbs.menu on p.id_selection equals m.id_selection
                           where p.availability == true
                           select new { p.id_dish, p.name_dish, m.id_selection, m.name_selection, p.price }).ToList <dynamic>();

            return(avaList);
        }