public bool UpdateNum(int userId, int cartId, int num) { if (userId <= 0 || cartId <= 0 || num <= 0) { return(false); } using (var cxt = DbContext(DbOperation.Write)) { cxt.BeginTransaction(); var repo = new ShoppingCartRepo(cxt); var flag = repo.UpdateNum(userId, cartId, num); if (flag) { cxt.Commit(); } else { cxt.Rollback(); } return(flag); } }