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From: "Phillip Smith" <phillip.smith@weatherbeeta.com.au>
To: "'Paul Lambert'" <paul.lambert@autoledgers.com.au>,
	"'pgsql-sql'" <pgsql-sql@postgresql.org>
Subject: Re: Quick question re foreign keys.
Date: Wed, 24 Oct 2007 12:14:57 +1000
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> My question therefore is, is it possible to create a foreign key that is
> conditional, i.e. only enforce the foreign key where the value in that
> table is not null.

My understanding from reading previous threads on this topic is the answer
is no, however you could make your own pseudo-foreign key using triggers to
do the same job, but only when your column is not null.

Not sure of the performance impact of doing this though - someone else may
be able to advise pros and cons in more detail.

Cheers,
~p


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