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From: fbd1@goliat.upc.es (practica fbd)
Message-Id: <9503271140.AA10960@goliat.upc.es>
Subject: A little question
To: postgres@postgres.Berkeley.EDU
Date: Mon, 27 Mar 1995 13:40:39 +0200 (MET DST)
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Resent-Date: Mon, 27 Mar 95 03:47:06 -0800
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	Hello, we are 3 students from Barcelona who are working with
Postgres 4.1. We have the next problem:

* We need to make reference from an object to another one, using some
kind of 'foreing key' but in a more object oriented style, and we don't
know how. We first tried to do this stuff: 

	create Thing (.....)\g
	create SubThing (reference_to_Thing = Thing)\g

and the answer was:

NOTICE:Mar 27 13:23:19:cannot create attribute of type Thing
WARN:Mar 27 13:23:19:use functions to get complex objects

Therefore we tried another solution which seems to work:

create People (name = text,
	       kmother = oid,
	       age = int4) \g

define function mother
(language = "postquel", returntype = People)
arg is (People)
as "retrieve (p.all)  
    from p in People
    where p.oid = $1.kmother" \g

append People (name = "Hillary Clinton", age = "40") \g
append People (name = "Chelsea Clinton", age = "14", 
		 kmother = p.oid)
from p in People
where p.name = "Hillary Clinton" \g

As we said before this works, but  is this the best way (the most
correct) to do it in Postgres?

			Thank You for your collaboration.

			Pedro, Oscar & Eduard : Postgres Team
			e-mail: fbd1@lsi.upc.es
			Facultat d'Informatica de Barcelona (F.I.B.),
			Universitat Politecnica de Catalunya (U.P.C.),
			Barcelona, Spain

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