Message-ID: <3A0004EA.3E7724F6@ucs.co.za>
Date: Wed, 01 Nov 2000 13:56:27 +0200
From: Grant Finnemore <gaf@ucs.co.za>
MIME-Version: 1.0
To: Marc Rohloff <Marc.Rohloff@eskom.co.za>
CC: pgsql-sql@postgresql.org
Subject: Re: Outer Joins
References: <s9ffea47.097@eskom.co.za>
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Marc,

I did not look at your queries, but outer joins are supported in the latest development version of PostgreSQL, and will be supported in the upcoming 7.1 release of the software - beta due soon.

Regards,
Grant

Marc Rohloff wrote:

> I've been looking at the open-source databases for a project I am working on and while reading about Postgres I saw that they do not support outer joins yet. I was intrigued by their solution of using a union query.
>
> Something Like:
> select a.col1, b.col2 from a,b where a.col1 = b.col2
> union
> select a.col1, NULL from a where a.col1 not in (select b.col2 from b)
>
> But I was wondering if the following would work (it does in some other databases)
>
> select a.col1, b.col2 from a,b
> where a.col1 = b.col2
>    or  b.col2 is null
>
> or maybe even
>
> select a.col1, b.col2 from a,b
> where a.col1 = b.col2
>    or  a.col1 not in (select b.col2 from b)
>
> These would seem to be far more efficient than a union query
> (I would try this but I don't have a Unix box at the moment to install PostgreSQL on!)
>
> Marc Rohloff

--
> Poorly planned software requires a genius to write it
> and a hero to use it.

Grant Finnemore BSc(Eng)  (mailto:gaf@ucs.co.za)
Software Engineer         Universal Computer Services
Tel  (+27)(11)712-1366    PO Box 31266 Braamfontein 2017, South Africa
Cell (+27)(82)604-5536    20th Floor, 209 Smit St., Braamfontein
Fax  (+27)(11)339-3421    Johannesburg, South Africa