Dear all,

I am a beginner with Hibernate and JPA.

I have a basic question regarding HQL and JPQL.

I might be using EJB 3.x, JPA and Hibernate for next project.

I ran some samples with EJB 3.x JPA with Hibenate as ORM framework.

My question is whether we have to use JPQL or HQL or both in entity classes and hibernate files?. If both are needed why both?

Is that something JPQL can do that HQL cannot do and vice versa. Is one better over other?

Thanks in Advance and Appreciate your inputs.


Best Regards

Harish

Just to make sure you know that: JPA is a specification on how to do OR-Mapping. Hibernate is one implementation of it, so it offers all JPA-features plus a some more useful features. So JPQL is also a specification on how to query objects, HQL is a kind of implementation.

Actually, when using Hibernate as ORM-Tool you will never feel there is a difference between JPQL and HQL. I have to admit that at this moment, I do not even know a big difference. I guess HQL gives you a few more features as hibernate offers more features than the JPA standard.

So don't worry about this, just start using hibernate while you read through the reference guide.

Thanks Merder. It was a good and relevant answer. Both JPA and JPQL are specifications and Hibernate and HQL are popular implementations.
It will help me in Hibernate and HQL world.

I have another related question

Can HQL queries be written in hibernate mapping xml file only or they can be embedded in Entity POJO classes as well?

Can persistence.xml contain HQL queries in JEE application?

Kindly let me know.

Thanks in Advance

Harish

Yes, you can include queries in your entities using annotations: http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#entity-mapping-query-hql

I would not map my queries in persistence.xml, but either use annotations or seperate mapping files, which are listed in persistence.xml.