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From "Mike Kienenberger" <>
Subject Re: Required Relations?
Date Fri, 23 Mar 2007 20:36:20 GMT
The mandatory nature of the relationship is based on the mandatory
nature of the underlying DB attributes.

Ie, if PAINTING.ARTIST_ID is mandatory, then the relationship
Painting.artist is also mandatory and must not be null.

On 3/23/07, Roja Buck <> wrote:
> All,
>    I am a little new to databases so I apologise if this query is
> particularly incompetent. I have created a series of tables all of which are
> related to one central table with that central table having relations of one
> to many with the rest of the tables. The problem I have however is that I
> want to be able to specify which of the fields (i.e. relations) are required
> within that central table. I understand how to do this for general
> attributes within a table however I see no way to say that a relation is
> required. Am I misunderstanding this fundamentally or simply missing
> something?
> An example of this using the examples in the getting started guide would be
> adding an artist who had not yet created any paintings, or similarly a
> galley with no paintings.
> Roja

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