JPQL JOINS with nested SELECT

Question

Can I do something like this on JPQL?

SELECT NEW com.MyDTO(p.a, p.b, q.c, q.d)
FROM
(SELECT r.* FROM MyDTO1 r ) p
LEF         


        

Answer 1

Yes you can!

You have to use native queries. Here is an example:

emf = Persistence.createEntityManagerFactory("TEST")    
EntityManager em = emf.createEntityManager();
String queryString = "SELECT ID FROM ( SELECT * FROM ADDRESS WHERE ID < 0)";
Query query = em.createNativeQuery(queryString);
List<BigDecimal> result = query.getResultList();

Answer 2

No, you can't. Quote from the documentation:

Note that HQL subqueries can occur only in the select or where clauses.