Re: Polymorphic delete help needed

On Thu, Jul 05, 2007 at 09:56:12PM -0500, Perry Smith wrote:
> I am doing a project using Ruby On Rails with PostgreSQL as the
> database.  I have not seen the term polymorphic used with databases
> except with Rails so I will quickly describe it.

You have now :)

http://archives.postgresql.org/sfpug/2005-04/msg00022.php

> Instead of holding just an id as a foreign key, the record holds a
> "type" field which is a string and an id.  The string is the name of
> the table to which the id applies.  (That is slightly simplified).

This is brittle by nature.  The above link sketches out a way to make
it stable.  If you have questions, ask :)

> The first problem

of many ;)

[other stuff snipped]

> that creates is it makes it hard to do a constraint
> on the name/id pair.

Let PostgreSQL work *for* you instead of picking a fight with it and
then piling on heaps of unnecessary code.

Cheers,
David.
--
David Fetter <david@fetter.org> http://fetter.org/
phone: +1 415 235 3778        AIM: dfetter666
                              Skype: davidfetter

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