Re: Help with query. (*)

From: Adam Haberlach <adam(at)newsnipple(dot)com>
To: "Diehl, Jeffrey" <jdiehl(at)sandia(dot)gov>
Cc: pgsql-sql(at)postgresql(dot)org, pgsql-general(at)postgresql(dot)org
Subject: Re: Help with query. (*)
Date: 2001-01-18 17:37:13
Message-ID: 20010118093713.B13028@newsnipple.com
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On Tue, Jan 16, 2001 at 01:42:45PM -0700, Diehl, Jeffrey wrote:
> I'm having difficulty writing a query which I really can't live without...
>
> I need to get a list of records from table A for which there are
> corresponding records in table B. I've tried to use the intersect clause,
> but it doesn't seem to work, or it runs far too long. For example:
>
> select * from A
> where 1=1
> intersect select * from A where
> B.x=A.x
> and A.y=B.y
> and A.z=B.z
> limit 100
>
> I need the most efficient method possible; my A tables have upward of 5
> Million records. The B table, btw, only has about 100 records.

I'm not totally sure what you are trying to do here, but it looks like you
may be more interested in:

SELECT * FROM a, b WHERE A.x = B.x AND A.y=B.y AND A.z=B.z;

Are you familiar with table joins?

--
Adam Haberlach |A cat spends her life conflicted between a
adam(at)newsnipple(dot)com |deep, passionate, and profound desire for
http://www.newsnipple.com |fish and an equally deep, passionate, and
'88 EX500 |profound desire to avoid getting wet.

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