Date now = new Date();
Order order1 = new Order();
entityManager.persist(order1);
Category category1 = new Category();
category1.setTitle("Informatique");
entityManager.persist(category1);
Category category2 = new Category();
category2.setTitle("Littérature");
entityManager.persist(category2);
Author author1 = new Author();
author1.setFirstName("Michel");
author1.setLastName("Martin");