// 2 get product details using id
        public static IEnumerable <PRODUCTS> GetProduct(int productNo)
        {
            IEnumerable <PRODUCTS> products = PRODUCTSDAL.GetAll();
            var product = from prod in products where prod.PRODUCTNO.Equals(productNo) select prod;

            return(product);
        }
 //3 getAll customers
 public static List <PRODUCTS> GetAllProducts() => PRODUCTSDAL.GetAll();