ElementCollection上的CriteriaBuilder.isEmpty与JPQL方法

// a lot of imports

@Entity
public class Thing {
    enum Type { FIRST, SECOND, THIRD };

    @SequenceGenerator(name = \"Thing_SeqGen\", sequenceName = \"Thing_Id_Seq\", initialValue = 1000)
    @Id
    @GeneratedValue(generator = \"Thing_SeqGen\")
    private int id;

    private String name = \"name\";

    @Enumerated(EnumType.STRING)
    @ElementCollection(targetClass = Thing.Type.class)
    @CollectionTable(name = \"TYPES\", joinColumns = { @JoinColumn(referencedColumnName = \"ID\", name = \"TYPE_ID\") })

    private Set<Thing.Type> typeSet = new HashSet<Thing.Type>();
    public static void main(final String[] args) {
        new Thing().start();
    }

    public void start() {
        final Thing firstThing = new Thing();
        firstThing.setName(\"First one\");
        firstThing.setTypeSet(EnumSet.of(Thing.Type.FIRST));
        final Thing firstAndSecondThing = new Thing();
        firstAndSecondThing.setName(\"Test2\");
        firstAndSecondThing.setTypeSet(EnumSet.of(Thing.Type.FIRST, Thing.Type.SECOND));
        final Thing bareThing = new Thing();
        bareThing.setName(\"Test3\");

        final EntityManagerFactory emf =  Persistence.createEntityManagerFactory(\"sandbox\");
        final EntityManager em = emf.createEntityManager();

        em.getTransaction().begin();
        em.persist(firstThing);
        em.persist(firstAndSecondThing);
        em.persist(bareThing);
        em.getTransaction().commit();

        em.getTransaction().begin();
        final CriteriaBuilder cb = em.getCriteriaBuilder();
        final CriteriaQuery<Thing> c = cb.createQuery(Thing.class);
        final Root<Thing> root = c.from(Thing.class);
        final Join<Thing, Set<Thing.Type>> typeJoin = root.join(\"typeSet\");

        c.select(root).distinct(true).where(cb.isEmpty(typeJoin));

        final List<Thing> results = em.createQuery(c).getResultList();

        em.getTransaction().commit();
    }

    // getter/setter methods omitted
}

select t from Thing t where t.typeSet is empty

CriteriaBuilder

SELECT DISTINCT t0.ID, t0.NAME FROM THING t0, TYPES t1 WHERE (((SELECT COUNT(t2.ID) FROM THING t2 WHERE (t1.TYPE_ID = t0.ID)) = 0) **AND (t1.TYPE_ID = t0.ID)**)

THING

(THING to, THING t1)