Message-ID: <4356F419.3010105@ashtonwoodshomes.com>
Date: Wed, 19 Oct 2005 21:34:17 -0400
From: Terry Fielder <terry@ashtonwoodshomes.com>
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To: Bryce W Nesbitt <bryce1@obviously.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: casting character varying to integer - order by numeric
References: <4356EC5D.4080706@obviously.com>
In-Reply-To: <4356EC5D.4080706@obviously.com>
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Check out the function to_number()

In particular here's an example...
If a field named section is text containing numbers:
ORDER BY to_number(t.section, text(99999999))

If the field can also contain non-numerals such as 3a, 3b, and you want 
3a to show first then do this:
ORDER BY to_number(t.section, text(99999999)), t.section

And if the field section can actually START with an alpha, then to 
prevent to_number from failing do this:
to_number(textcat('0', t.section), text(99999999)), t.section

Terry

Bryce W Nesbitt wrote:
> How can I force a character field to sort as a numeric field?
> I've got something like this:
> 
> Postgres=> SELECT username,last_name
>                  FROM eg_member ORDER BY username;
> ----------+-----------
> 0120     | Foley
> 1        | Sullivan
> 10       | Guest
> 11       | User
> (5 rows)
> 
> (I can't change the field type).  I tried:
> 
>  SELECT username,last_name
>  FROM eg_member ORDER BY username::integer;
> 
> But postgres 7 rejects this with "ERROR:  cannot cast type character 
> varying to integer".  Is there a way to force numeric sort order?  I 
> tried a variety of functions, such as to_char() and convert() without 
> any luck.  Thanks for your insight!
> 
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 2: Don't 'kill -9' the postmaster
> 

-- 
Terry Fielder
terry@greatgulfhomes.com
Associate Director Software Development and Deployment
Great Gulf Homes / Ashton Woods Homes
Fax: (416) 441-9085