Re: outer joins

From: Andrus Adamchik (andru..bjectstyle.org)
Date: Wed Jan 13 2010 - 04:57:59 EST

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    On Jan 13, 2010, at 11:44 AM, Aristedes Maniatis wrote:

    > On 13/01/10 6:53 PM, Andrus Adamchik wrote:
    >> http://cayenne.apache.org/doc/path-expressions.html ("Aliases in
    >> Path
    >> Expressions")
    >
    > Just to be clear, does Cayenne always produce a LEFT OUTER JOIN when
    > using the "+" notation?

    Yes.

    > The example at the top of the page with "toArtist.exhibitArray
    > +.closingDate" when used in a query will effectively mean: "find all
    > paintings by an artist who has an exhibition closing on date x, and
    > also find all paintings by artists with no exhibitions". Does that
    > sound right?

    Yes.

    > Also, I'm not sure of the point being made in the last section
    > "Matching Path Expressions".

    Maybe that needs to be more explicit. The point is that if your path
    on the left resolves to an attribute of a certain type, the value on
    the right must be of that type as well (and there's no automatic type
    conversions). I guess we can expand that to explain some variations of
    this rule (e.g. instead of DataObject, you can pass ObjectId, etc.)

    Andrus



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