Re: Join question

From: "Williams, Travis L, NEO" <tlw(at)att(dot)com>
To: "Thomas A(dot) Lowery" <tlowery(at)stlowery(dot)net>, <pgsql-general(at)postgresql(dot)org>
Subject: Re: Join question
Date: 2003-08-29 01:32:39
Message-ID: AB815D267EC31A4693CC24D234F8291605A0C663@ACCLUST02EVS1.ugd.att.com
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Sure.. if it works.. I'm just trying to not have to make multiple calls
to the DB.. I'll try it out..

Thanks,

Travis

-----Original Message-----
From: Thomas A. Lowery [mailto:tlowery(at)stlowery(dot)net]
Sent: Thursday, August 28, 2003 8:06 PM
To: pgsql-general(at)postgresql(dot)org
Subject: Re: [GENERAL] Join question

Does using a union count as one query?

select a from tst_1 where b is null
union
select d from tst_2 t2 join tst_1 t1 on (t1.b = t2.c)
where t1.b is NOT null

On Thu, Aug 28, 2003 at 05:55:27PM -0400, Williams, Travis L, NEO wrote:
> Question,
>
> I have a table (1) with 2 col (a & b) where b can sometimes be null. I
> need a query that if B is null I get back the contents of A.. but if B
> is not null I do a join on it and table (2) col c to get the contents
> of table (2) col d.. I can do this in multiple queries.. but was
> wondering if I could do it in 1.

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