From: Josh Berkus <josh@agliodbs.com>
To: Patrick Hatcher <PHatcher@macys.com>
To: pgsql-sql@postgresql.org
Subject: Re: Is it possible to use a field from another table as part of a query?
Date: Fri, 19 Jul 2002 11:54:27 -0700
Message-ID: <200207191154.27095.josh@agliodbs.com> (raw)
In-Reply-To: <OF70E61741.D785C8E7-ON88256BFB.00664267-88256BFB.00664F48@fds.com>
References: <OF70E61741.D785C8E7-ON88256BFB.00664267-88256BFB.00664F48@fds.com>
Partick,
> I have a table that contains a VARCHAR field with data formatted as such:
> 12,44,13,225
> what I would like to do is use this field in a query to another table such
> as:
1. Since you are a smart guy, I'm assuming that this "delimited" VARCHAR data
is legacy data that you don't have a choice about re-structuring. Because,
of course, the normalized way to store the data would be in a subtable, not a
VARCHAR field.
>
> CREATE TABLE category_tree (
> tree varchar(200)
> ) WITH OIDS;
>
> Select * from mdc_products
> where keyf_category_home IN (select tree from category_tree)
>
> However, my keyf_category_home field is an INT4. Is there a way to parse
> out the tree field so that I can define it as INT4?
Well, this is easiest thing to do:
Select * from mdc_products
where EXISTS
(select tree from category_tree
WHERE tree ~ ('(^|,)' || keyf_category_home || '(,|$)'));
(somebody please correct my regexp if I've made an error)
... but that's impossible to index. If the table category_tree doesn't
change often, I'd write a program to parse the data and build a normalized
subtable containg a vertical colum of tree values.
--
-Josh Berkus
Aglio Database Solutions
San Francisco
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To: pgsql-sql@postgresql.org
Cc: josh@agliodbs.com, PHatcher@macys.com
Subject: Re: Is it possible to use a field from another table as part of a query?
In-Reply-To: <200207191154.27095.josh@agliodbs.com>
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