RE: Sequential select queries...??

From: "Henshall, Stuart - WCP" <SHenshall(at)westcountrypublications(dot)co(dot)uk>
To: "'Mark Mikulec'" <mm98au(at)badger(dot)ac(dot)brocku(dot)ca>, pgsql-sql(at)postgresql(dot)org
Subject: RE: Sequential select queries...??
Date: 2001-08-21 10:43:05
Message-ID: E2870D8CE1CCD311BAF50008C71EDE8E01F74682@MAIL_EXCHANGE
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If you want to know for each individual one wether both equal or not you
could do:
SELECT *,NOT ((name=description) IS NULL) AND (name=description) AS both
FROM t WHERE name='bleh' OR description='bleh';
If you wanted totals of the same you could do:
SELECT count(*) AS tot,NOT ((name=description) IS NULL) AND
(name=description) AS both FROM t WHERE name='bleh' OR description='bleh'
GROUP BY NOT ((name=description) IS NULL AND (name=description);
I think this should be more efficient than UNIONs, but am not an expert on
the query planner or executor.
- Stuart

> -----Original Message-----
> From: Mark Mikulec [SMTP:mm98au(at)badger(dot)ac(dot)brocku(dot)ca]
> Sent: Wednesday, August 15, 2001 1:41 AM
> To: pgsql-sql(at)postgresql(dot)org
> Subject: Sequential select queries...??
>
> Hello,
>
> At first I thought what I was trying to do was simple and could be done
> easily - but alas, I've spent way too much time and could not figure out
> how to get the results in question.
>
> Let's say I have a table T comprised of id of type integer, name and
> description both of type text.
>
> What i'd like to do is the following:
>
> Select id from T where name = 'bleh';
>
> and
>
> Select id from T where description = 'bleh';
>
> and result both results in the same result set. That is, duplicate id's
> if they appear. So then I could do a GROUP BY and a COUNT to see how
> many appeared in only one, and how many appeared in both.
>
> Could someone help me? I've tried countless different sql queries, can't
> seem to get one to work. If I can just get those duplicate id's in the
> query.. then I'd be laughing and then I can complete my task.
>
> Thanks in advance,
>
> Mark
>

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