I started to work with eclipse link and from what I read in the net the eclipse link is some kind of JPA implementation and you are not working directly with DB code when you are using eclipse link you are working with objects.
My question is what is this if not DB command?
Query q = em
.createQuery("SELECT p FROM Person p WHERE p.firstName = :firstName AND p.lastName = :lastName");
It’s JPQL. You can find more here