Linq使用范围事务

Northwnd db = new Northwnd(@"c:\northwnd.mdf");
            using (TransactionScope ts = new TransactionScope())
            {
                try
                {
                    Product prod1 = db.Products.First(p => p.ProductID == 4);
                    Product prod2 = db.Products.First(p => p.ProductID == 5);
                    prod1.UnitsInStock -= 3;
                    prod2.UnitsInStock -= 5;
                    db.SubmitChanges();
      ts.Complete();
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.Message);
                }
            }