private string AddOrUpdateFoodInOrder(string orderID, List <Food> orderItems)
        {
            Table <DAL.FoodCalled> foodOrderTable = GetFoodCalledTable();

            DeleteFoodInOrder(orderID);
            FoodManager       fdManager  = new FoodManager();
            IngredientManager igrManager = new IngredientManager();
            StockManager      stkManager = new StockManager();

            foreach (Food fd in orderItems)
            {
                DAL.FoodCalled data = new DAL.FoodCalled();
                try
                {
                    data.orderID  = orderID;
                    data.foodID   = fdManager.GetFoodIDByName(fd.Name);
                    data.quantity = fd.Quantity;

                    // Update quantity in stock
                    foreach (Ingredient igr in igrManager.GetFoodIngredientList(fd.Name))
                    {
                        string err = stkManager.DecreaseIngredientQuantityInStock(igrManager.GetIngredientDetailsID(igr.Name), data.quantity * int.Parse(igr.Quantity.ToString()));
                        if (err != "")
                        {
                            return(err);
                        }
                    }

                    foodOrderTable.InsertOnSubmit(data);
                    foodOrderTable.Context.SubmitChanges();
                }
                catch (Exception ex)
                {
                    return(ex.Message);
                }
            }

            return("");
        }