Date: Mon, 29 Aug 2005 16:24:45 -0700
From: David Fetter <david@fetter.org>
To: "Marc G. Fournier" <scrappy@postgresql.org>
Cc: pgsql-hackers@postgresql.org
Subject: Re: ALTER TABLE ( smallinto -> boolean ) ...
Message-ID: <20050829232445.GE13074@fetter.org>
References: <20050829201253.X1044@ganymede.hub.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20050829201253.X1044@ganymede.hub.org>
User-Agent: Mutt/1.4.2.1i

On Mon, Aug 29, 2005 at 08:15:41PM -0300, Marc G. Fournier wrote:
> 
> I have a table with several 'smallint' fields that I'd like to convert to 
> booleean ... the data in each is either 0 or 1, and:
> 
> # select '1'::boolean;
>  bool
> ------
>  t
> (1 row)
> # select '0'::boolean;
>  bool
> ------
>  f
> (1 row)
> 
> so they do cast as expected ... but, if I try to do the ALTER, I get:
> 
> # ALTER TABLE table ALTER COLUMN field1 type boolean;
> ERROR:  column "field1" cannot be cast to type "pg_catalog.bool"

> Should this not work?  If not, is there a way to do it so that it will, 
> without having to reload the whole table?

ALTER TABLE "table" ALTER COLUMN field1 TYPE boolean
    USING CASE field1 WHEN 0 THEN false ELSE true END;
/* or something to this effect */

HTH :)

Cheers,
D
-- 
David Fetter david@fetter.org http://fetter.org/
phone: +1 510 893 6100   mobile: +1 415 235 3778

Remember to vote!