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Criteria API: left outer join [message #634346]

Thu, 21 October 2010 11:09

Patrick Haun

Messages: 30
Registered: October 2009

Member

I try to convert a JPQL statement to the criteria API. The JPQL query uses a LEFT OUTER JOIN to create the result.

I tried this using the criteria api:

 final Join<Object, Object> join = root.join("applInstance", JoinType.LEFT);

Unfortunately the resulting sql code doesn't contain an left outer join.

The JPQL query:

SELECT events FROM Events events LEFT JOIN events.applInstance applInstance

[Updated on: Thu, 21 October 2010 11:27]

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Re: Criteria API: left outer join [message #634394 is a reply to message #634346]

Thu, 21 October 2010 14:31

Chris Delahunt

Messages: 1249
Registered: July 2009

Senior Member

Hello,

Are you trying to have the events.applInstance fetched with the returned event objects? If the join is not used in the selection criteria, an outer join will do nothing other than add extra processing work to the database query. You might want to use the fetch instead.

That said, the query adds the join to the SQL for for me on the latest version of EclipseLink (2.2 nightly build). Which version are you using, and what is the SQL generated for both queries?

Best Regards,
Chris

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Re: Criteria API: left outer join [message #634618 is a reply to message #634346]

Fri, 22 October 2010 12:58

Patrick Haun

Messages: 30
Registered: October 2009

Member

I found a solution. I didn't use the join object in the where clause.

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