Hibernate - (HQL and JPQL) Implicit joins (path expressions)

Another means of adding to the scope of object model types available to the query is through the use of implicit joins or path expressions.

Simple implicit join example

List<Phone> phones = entityManager.createQuery(
"select ph " +
"from Phone ph " +
"where ph.person.address = :address ", Phone.class )
.setParameter( "address", address )
.getResultList();

// same as
List<Phone> phones = entityManager.createQuery(
"select ph " +
"from Phone ph " +
"join ph.person pr " +
"where pr.address = :address ", Phone.class )
.setParameter( "address", address)
.getResultList();

Reused implicit join

List<Phone> phones = entityManager.createQuery(
"select ph " +
"from Phone ph " +
"where ph.person.address = :address " +
"  and ph.person.createdOn > :timestamp", Phone.class )
.setParameter( "address", address )
.setParameter( "timestamp", timestamp )
.getResultList();

//same as
List<Phone> phones = entityManager.createQuery(
"select ph " +
"from Phone ph " +
"inner join ph.person pr " +
"where pr.address = :address " +
"  and pr.createdOn > :timestamp", Phone.class )
.setParameter( "address", address )
.setParameter( "timestamp", timestamp )
.getResultList();