EJB3QL and SQL queries are represented by an instance of javax.persistence.Query. This interface offers methods for parameter binding, result set handling, and for execution of the query. Queries are always created using the current entity manager:

List cats = em.createQuery(
    "select cat from Cat as cat where cat.birthdate < ?1")
    .setParameter(1, date, TemporalType.DATE)
    .getResultList();

List mothers = em.createQuery(
    "select mother from Cat as cat join cat.mother as mother where cat.name = ?1")
    .setParameter(1, name)
    .getResultList();

List kittens = em.createQuery(
    "from Cat as cat where cat.mother = ?1")
    .setEntity(1, pk)
    .getResultList();

Cat mother = (Cat) em.createQuery(
    "select cat.mother from Cat as cat where cat = ?1")
    .setParameter(1, izi)
    .getSingleResult();

A query is usually executed by invoking getResultList(). This method loads the resulting instances of the query completly into memory. Entity instances retrieved by a query are in persistent state. The getSingleResult() method offers a shortcut if you know your query will only return a single object.