Re: Hibernate mapping for sql join
Stefanie Ertheld wrote:
However, it seems like you need an "EventManager" instance for it to
work,
and I read it was something like the Session / SessionManager, or
something "above" it.
You might want to say what you mean by "above"; I have no clue.
It's not a bad idea to google around as you prepare your Usenet post to get
the exact terms.
'Session' and 'SessionFactory' are classes in the Hibernate library, within
the org.hibernate... namespaces.
'EntityManager' and 'EntityManagerFactory' are the Java standard JPA (Java
Persistence API) equivalents, also supported by Hibernate. They are newer and
preferable. Forget altogether about the 'Session' approach and just use JPA.
Currently we have Spring managing the Hibernate Session - and it was
said the EventManager could be
wirred into Spring too - but is it possible to have both Session and
EventManager parallely?
No.
When I said I don't want to do it in HQL, I meant because I know pure
SQL better.
Different world. SQL is (roughly) set oriented; JQL (the JPA version of HQL)
is roughly object oriented.
The point of Hibernate is to give the application an object model. That is
different from a data model, and very different from a table model.
Don't try to manage the data; that's what the session or data manager do.
SQL and HQL/JPQL are different, serving different purposes, in different
semantic spaces. They are not plugins for each other.
Ignorance is never an excuse not to learn; /au contraire/ it's an opportunity
to learn. It's a bit unfortunate that you're thinking, "I know SQL better."
This will lead to misinterpretation of the ORM tool and major inefficiencies
in the code.
That said, a SQL-based approach is just fine. Just don't use Hibernate with it.
I'm completely unconvinced that Spring brings anything to this party.
But now that you come up with JP[Q]L - this seems even more complicated.
Couldn't it be done with HQL too? The Pojo I am using i [div] have wired
into Hibernate with a mapping -
it's just a special, flat mapping without any reference to other
entities.
That's nice. Vague descriptions don't add much to the discussion.
The JPA approach is simpler, but you need use it (or the older 'Session' way)
from an object-oriented perspective, which you clearly are not doing. If you
prefer the table-oriented approach forget ORMs and go with straight JDBC.
--
Lew
Honi soit qui mal y pense.