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From: Jacob Sparre Andersen <jacob@jacob-sparre.dk>
Newsgroups: comp.lang.ada
Subject: Re: GNATColl ORM problem (foreign key twins)
Date: Wed, 30 Oct 2013 18:48:03 +0100
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2013-10-30T18:48:03+01:00
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Simon Wright wrote:

> I think that the problem is that the thing in brackets is not meant to
> be the PK in the table that is being referenced, it's the name of the
> reverse relationship. Look for 'revert_name' under [1] (I'm pretty
> sure this should be 'reverse_name', BTW).

Thanks.  It looks like you are correct.

> | TABLE    | category_subsets     | category_subset |  | Item categorisations |
> | superset | FK categories(parents) | NOT NULL        |  |                    |
> | subset   | FK categories(children) | NOT NULL        |  |                    |

It can be even simpler:

| TABLE    | category_subsets | category_subset |  | Item categorisations |
| superset | FK categories    | NOT NULL        |  |                      |
| subset   | FK categories    | NOT NULL        |  |                      |

> [1] http://docs.adacore.com/gnatcoll-docs/sql.html#database-schema

The formal grammar for foreign keys might be improved by making it
explicit that the reverse_name isn't required.

Once more; thanks for clarifying the documentation for me.

Greetings,

Jacob
-- 
"... while the C compiler will happily generate code for
 almost anything produced by leaning on the keyboard."