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From "Øyvind Harboe" <>
Subject Re: Detecting when outer joins are needed [Was: Cayenne does not throw an exception when an outer join is attempted]
Date Mon, 28 Aug 2006 05:54:39 GMT
On 8/25/06, Andrus Adamchik <> wrote:
> On Aug 23, 2006, at 11:35 PM, Mike Kienenberger wrote:
> > Here's where I'm finding that I need outer joins:
> >
> > 1) If two qualifiers for a non-mandatory relationship path are or'd
> > together.   This is also what Øyvind Harboe reported.   It may be that
> > the non-mandatory part is irrelevent.
> >
> > 2) If using noMatchExp on a non-null value for a non-mandatory
> > relationship path.
> Thanks Mike - that makes sense. I think "non mandatory" part is
> relevant. Not sure that we need to catch it though. IMO this should
> be left as an exercise to the user.

I could really do with having this exercise clearly formulated in doc/wiki...

I have a hard time explaining my peers what precisely it is that they
should be looking for.

Also, how do I know that I've got the complete list of gotchas?

Is it in theory possible to detect this during runtime?

It would be nice to be able to add some runtime checks that generated
expressions aren't running into this problem.

Øyvind Harboe

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