How to have multiple conditions in JPQL join

问题:

I want to join two tables using JPQL:

SELECT * FROM A LEFT JOIN 
B ON A.ID = B.A_ID AND B.lng = 'en'

The important part is AND B.lng = 'en'

Is this possible in JPQL?

回答1:

JPA 2.0 does not support an ON clause, but the JPA 2.1 draft does.

EclipseLink 2.4 supports an ON clause.

See, http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Querying/JPQL#ON

回答2:

Yes it is possible, there is a similar question here. However, if your entities are mapped, you should be able to access them in a query.