From: Aaron Bono <postgresql@aranya.com>
To: pgsql-sql@postgresql.org
Subject: Re: query to select a linked list
Date: Wed, 9 May 2007 08:29:22 -0500
Message-ID: <bf05e51c0705090629l7232a6d2we87170b2168c1c82@mail.gmail.com> (raw)
In-Reply-To: <20070509125520.GA17497@apartia.fr>
References: <20070509125520.GA17497@apartia.fr>
On 5/9/07, Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
wrote:
>
> Hi,
>
> To build a threaded forum application I came up the following schema:
>
> forum
> ------
> id_forum | integer| not null default
> nextval('forum_id_forum_seq'::regclass)
> id_parent| integer|
> subject | text | not null
> message | text |
>
> Each message a unique id_forum and an id_parent pointing to the replied
> post (empty if first post).
>
> How can I build an elegant query to select all messages in a thread?
>
> Thanks,
>
Unlike Oracle, PostgreSQL doesn't have anything like a connect by so you
would need to write your own stored procedure for that (if new versions of
PostgreSQL will have connect by, let me know guys).
What I did was add a little redundancy to my forum tables and had a table
structure kind of like this:
forum
forum_id BIGSERIAL PK,
name VARCHAR(50)
forum_topic
forum_topic_id BIGSERIAL PK,
forum_id BIGINT FK to forum
forum_post
forum_post_id BIGSERIAL PK,
create_dt TIMESTAMP,
subject VARCHAR(255),
message TEXT,
forum_topic_id BIGINT FK to forum_topic
and if you want threading, you add a parent_forum_post_id to forum_post
(this is where you get the redundancy since only the top forum_post record
needs a reference to forum_topic and forum_topic wouldn't even really be
needed.
-Aaron
--
==================================================================
Aaron Bono
Aranya Software Technologies, Inc.
http://www.aranya.comhttp://codeelixir.com
==================================================================
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Cc: postgresql@aranya.com
Subject: Re: query to select a linked list
In-Reply-To: <bf05e51c0705090629l7232a6d2we87170b2168c1c82@mail.gmail.com>
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