public ActionResult AddToCart(int?id, int?quantity) { var user = User.Identity.Name; if (User.Identity.IsAuthenticated) { Book book = db.Books.Where(x => x.BookID == id).First(); Customer customer = db.Customers.Where(x => x.Username == user).First(); Shopping cart = db.Shoppings.Where(x => x.CustomerID == customer.CustomerID).First(); // Cart_Book cb = db.Cart_Book.Where(x => x.CartID == cart.CartID && x.BookID == id).First(); if (quantity > book.Inventory) { quantity = book.Inventory; } db.usp_AddBookToCart(cart.CartID, book.BookID, customer.CustomerID, quantity); } else { return(RedirectToAction("Login", "Account", null)); } return(RedirectToAction("Index", "Book", null)); }