internal void insertReceipt(Receipt receip, Customer customer)
        {
            using (BSPetShopEntities context = new BSPetShopEntities())
            {
                var customerWithID = from c in context.CustomerSet where c.PhoneNumber.Equals(customer.phonenumber) select c;
                context.ReceiptSet.Add(new ReceiptSet() { Totalprice = receip.totalPrice().ToString(), Date = receip.date, Customer_Id = customerWithID.Single().Id }); context.SaveChanges();

                foreach (Animal a in receip.animals)
                {
                    Type birdType = typeof(Bird);
                    Type fishType = typeof(Fish);
                    var receipt = from r in context.ReceiptSet where r.Date == receip.date && r.Customer_Id == customer.id select r;

                    if (a.GetType() == birdType)
                    {
                        var query = from b in context.BirdSet where b.Id == a.id select b;

                        foreach (BirdSet b in query)
                        {
                            b.Receipt_Id = receipt.Single().Id;
                        }

                        context.SaveChanges();
                    } else
                    {
                        var queryF = from f in context.FishSet where f.Id == a.id select f;
                        foreach (FishSet f in queryF)
                        {
                            f.Receipt_Id = receipt.Single().Id;
                        }

                        context.SaveChanges();
                    }
                }

            }
        }