Folks,
Does RDBO support defining a "some time" or "maybe" relationship?

Consider the following:

    CREATE TABLE locations (
        id      INT,

        ...

    );

    CREATE TABLE companies (
        id              INT,
        location_id     INT NOT NULL
            REFERENCES locations(id),
    
        ...
    );

    CREATE TABLE exhibitions (
        id              INT,
        location_id     INT NOT NULL
            REFERENCES locations(id),

        ...
    );

I have no problem creating the relationship from Company and Exhibition
to Location.

What I'd like to create is a "company" relationship in Exhibition that
returns the Company that has the same location_id as itself.  It is of
course conceivable that a given exhibition has a location_id not used by
a Company so there would be no Company object to return.

Likewise, I'd like an "exhibitions" relationship in Company that returns
all the exhibitions that have the same location_id as the company.

I'm not sure if RDBO supports this, and if it does, how to formulate the
syntax.

Thank you.
    -- Robert

-- 
Robert James Kaes                  WormBytes Consulting and Contracting
http://tinyproxy.sourceforge.net/              http://www.wormbytes.ca/

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