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Re: SQL, related records (quotes)

From: Stefan Rybacki <stefan.rybacki_at_gmx.net>
Date: Sun, 26 Jun 2005 10:56:02 +0200
Message-ID: <3i78t2Fk4c3tU1@individual.net>


Dan Guntermann wrote:
 >...
> But alas, not many implementations allow for assertions of antisymmetry,
> though it could be done with a trigger. This approach would enforce the
> condition that
> for all (child, parent) relationships that are members of hierarchies, there
> does not exist a tuple of (parent, child). It also has the limiting factor
> of disallowing single node hierarchies.

You meant non-symmetry since anti-symmetry says: you can have (child, parent) and (parent, child) at the same time execept parent=child

Just mentioned ;) (I know antisymmetry works here since you said you don't allow reflexive tupels)

Regards
Stefan

 >... Received on Sun Jun 26 2005 - 03:56:02 CDT

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