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Re: Join question

From: "Thomas A(dot) Lowery" <tlowery(at)stlowery(dot)net>
To: "Williams, Travis L, NEO" <tlw(at)att(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Join question
Date: 2003-08-29 01:54:15
Message-ID: 20030829015415.GA4265@stlowery.net (view raw or flat)
Thread:
Lists: pgsql-general
On Thu, Aug 28, 2003 at 09:46:34PM -0400, Williams, Travis L, NEO wrote:
> That would probably work great.. except I screwed my question up..  Let
> me try again and this time think before I write
> 
> I have a table1 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 "select d from table2 where d like '%b%'"  There is
> nothing to join between table1 & table2 (unless you can join on likes ;)
> ).

So the second select uses the value of table1 column b in the like condition?

> -----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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