Re: [eclipselink-users] Outer joined one-to-many question

[Andrei Ilitchev <andrei.ilitchev@xxxxxxxxxx>]

How about:

SELECT p.id
  FROM Parent p
  LEFT OUTER JOIN p.children children
 WHERE
   children IS EMPTY OR
   EXISTS(SELECT child FROM Child child WHERE (child IN (p.children) 
AND child.x = 'y'))



On 8/19/2013 2:15 PM, Laird Nelson wrote:
> On Mon, Aug 19, 2013 at 2:04 PM, Andrei Ilitchev
> <andrei.ilitchev@xxxxxxxxxx <mailto:andrei.ilitchev@xxxxxxxxxx>> wrote:
>
>     Should be something like:
>
>     "SELECT e FROM Employee e LEFT OUTER JOIN e.projects projects WHERE
>     (e.projects IS EMPTY OR EXISTS(SELECT p FROM Project p WHERE (p
>     IN(e.projects) AND p.name <http://p.name> LIKE 'A%')))"
>
>
> Now I'm even more confused.  :-)
>
> I get the gist of what you're saying.
>
> Now I'm getting NullPointerExceptions from inside EclipseLink.
>
> My old query said this:
>
> SELECT p.id <http://p.id>
>    FROM Parent p
>    LEFT OUTER JOIN p.children child
>   WHERE child IS NULL OR child.x = 'y' ....
>
> My new query says this:
>
> SELECT p.id <http://p.id>
>    FROM Parent p
>    LEFT OUTER JOIN p.children child
>   WHERE child IS EMPTY OR child.x = 'y' ....
>
> Doing this causes this:
>
> Query failed to prepare, unexpected error occurred:
> [java.lang.NullPointerException].
> Internal Exception: java.lang.NullPointerException
> Query: JPAQuery(name="Parent.foobar" )
> at
> org.eclipse.persistence.exceptions.QueryException.prepareFailed(QueryException.java:1555)
> at
> org.eclipse.persistence.queries.DatabaseQuery.checkPrepare(DatabaseQuery.java:625)
> at
> org.eclipse.persistence.queries.DatabaseQuery.checkPrepare(DatabaseQuery.java:575)
> at
> org.eclipse.persistence.internal.sessions.AbstractSession.processJPAQueries(AbstractSession.java:2161)
> at
> org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.initializeDescriptors(DatabaseSessionImpl.java:442)
> at
> org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.postConnectDatasource(DatabaseSessionImpl.java:676)
> at
> org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.login(DatabaseSessionImpl.java:634)
> at
> org.eclipse.persistence.internal.jpa.EntityManagerFactoryProvider.login(EntityManagerFactoryProvider.java:208)
> at
> org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:488)
> ... 39 more
> Caused by: java.lang.NullPointerException
> at
> org.eclipse.persistence.internal.jpa.parsing.EmptyCollectionComparisonNode.generateExpression(EmptyCollectionComparisonNode.java:57)
> Is there something about the join alias ("child") that is causing this?
> Or...?
>
> Best,
> Laird
> --
> http://about.me/lairdnelson
>
>
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