4.4. オブジェクトの問い合わせ

Iterator<Cat[]> kittensAndMothers = 
  em.createQuery("select kitten, mother from Cat kitten join kitten.mother mother").getResultList().iterator();
  while (kittensAndMothers.hasNext()) {
     Cat[] tuple = kittensAndMothers.next();
     Cat kitten = tuple[0];
     Cat mother = tuple[1];
  } 
    ....
}

Iterator<Object[]> results = em.createQuery(
        "select cat.color, min(cat.birthdate), count(cat) from Cat cat " +
        "group by cat.color")
        .getResultList()
        .iterator();

while ( results.hasNext() ) {
    Object[] row = results.next();
    Color type = (Color) row[0];
    Date oldest = (Date) row[1];
    Integer count = (Integer) row[2];
    .....
}

// Named parameter (preferred)
Query q = em.createQuery("select cat from DomesticCat cat where cat.name = :name");
q.setParameter("name", "Fritz");
List cats = q.getResultList();

// Positional parameter
Query q = em.createQuery("select cat from DomesticCat cat where cat.name = ?1");
q.setParameter(1, "Izi");
List cats = q.getResultList();

// Named parameter list
List names = new ArrayList();
names.add("Izi");
names.add("Fritz");
Query q = em.createQuery("select cat from DomesticCat cat where cat.name in (:namesList)");
q.setParameter("namesList", names);
List cats = q.getResultList();

Query q = em.createQuery("select cat from DomesticCat cat");
q.setFirstResult(20);
q.setMaxResults(10);
List cats = q.getResultList(); //return cats from the 20th position to 29th

@javax.persistence.NamedQuery(name="eg.DomesticCat.by.name.and.minimum.weight", 
  query="select cat from eg.DomesticCat as cat  where cat.name = ?1 and cat.weight > ?2")

Query q = em.createNamedQuery("eg.DomesticCat.by.name.and.minimum.weight");
q.setParameter(1, name);
q.setParameter(2, minWeight);
List cats = q.getResultList();

@SqlResultSetMapping(name="getItem", entities = 
        @EntityResult(entityClass=org.hibernate.ejb.test.Item.class, fields= {
            @FieldResult(name="name", column="itemname"),
            @FieldResult(name="descr", column="itemdescription")
        })
)

Query q = em.createNativeQuery("select name as itemname, descr as itemdescription from Item", "getItem");
item = (Item) q.getSingleResult(); //from a resultset

Query q = em.createNativeQuery("select * from Item", Item.class);
item = (Item) q.getSingleResult(); //from a class columns names match the mapping