Re: EOQualifier or...?
Re: EOQualifier or...?
- Subject: Re: EOQualifier or...?
- From: Chuck Hill <email@hidden>
- Date: Thu, 23 Apr 2009 09:28:11 -0700
On Apr 23, 2009, at 9:25 AM, Mike Schrag wrote:
oddly, you can set a join semantic on an eorelationship, but i don't
think they actually expose that API anywhere else?
No, not that I have seen. I don't think that would help here, would
it? He wants only the rows that don't have corresponding rows.
Chuck
On Apr 23, 2009, at 12:20 PM, Chuck Hill wrote:
On Apr 22, 2009, at 3:21 PM, John Ours wrote:
I have a situation where I have an entity "Item" that is related
to many "Picture" items. I'm trying to fetch all "Items" that
have no related "Pictures"...in sql I would write a query like:
SELECT * FROM Item i
LEFT JOIN Picture p ON i.id = p.itemID
WHERE p.id is null
In other words I'd like to select all where Item.pictures.count ==
0. What's the easiest / best / most correct way to do this with EO?
Plain EOF is probably not going to do this. You could try an
Equals qualifier with null or an empty array and see if you get
lucky. Otherwise, you need to look into the additional qualifiers
in Wonder and the Houdah frameworks. None of these are super well
documented as to all of their possibilities, so you often need to
poke around in them and sometimes come at your problem from a
different angle. I don't recall off the top of my head which
combination will get you what you want.
Chuck
--
Chuck Hill Senior Consultant / VP Development
Come to WOWODC'09 in San Fran this June!
http://www.wocommunity.org/wowodc09/
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--
Chuck Hill Senior Consultant / VP Development
Come to WOWODC'09 in San Fran this June!
http://www.wocommunity.org/wowodc09/
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