From: David Fetter <shackle@fetter.org>
Subject: Re: Optional join
References: <sf3b6707.030@ems-t.ca>
User-Agent: tin/1.6.0-20030714 ("Vatersay") (UNIX) (Linux/2.4.20-8 (i686))
Message-ID: <nXidnVVfXr8X6aGiXTWc-w@speakeasy.net>
Date: Fri, 15 Aug 2003 00:50:02 -0500
Lines: 38
To: pgsql-sql@postgresql.org

"Slawek Jarosz" <Jarosz.S@ems-t.ca> wrote:
> Hi,

> I trying to write a query that will join 2 tables.   Here's the
> concept:

> Table 1: table1, primary key pk1
> Table 2: table2, primary key pk2

> One of the fields (f2) in table2 contains either the primary key of
> table1 or a NULL value.  So normally a pretty basic query:

> SELECT table1.*, table2.pk2
> FROM table1, table2 WHERE table2.f2 = table1.pk1;  

> BUT what I would like to do is show all records of Table 1 even if
> there is no match in Table 2.  Meaning that the reults could be 

> table1...   table2.pk2
> table1...   NULL

> Doable?

Yes.

SELECT table1.*, table2.pk2
FROM table1 LEFT OUTER JOIN table2 ON (table1.pk1 = table2.pk2);

HTH :)

Cheers,
D
-- 
David Fetter david@fetter.org http://fetter.org/
phone: +1 510 893 6100    cell: +1 415 235 3778

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