Message-ID: <4292DBAA.7030408@archonet.com>
Date: Tue, 24 May 2005 08:45:46 +0100
From: Richard Huxton <dev@archonet.com>
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To: Timo Roessner <timo.roessner@gmx.net>
Cc: pgsql-sql@postgresql.org
Subject: Re: datatype conversion on postgresql 7.4.1
References: <42906D06.3090200@gmx.net>
In-Reply-To: <42906D06.3090200@gmx.net>
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Timo Roessner wrote:
> and if i try something like:
> 
> alter table fragment alter column  x type numeric(15,2)
> 
> i get an syntax error, so this seems to be no feature in 7.4.1 (didnt 
> find anything like that in the docs too....)
> 
> what can i do to solve this? there must be some way in postgresql 7.4.1, 
> if there is no way to do that, i have to
> build up the whole database from scratch........there must be a way to 
> convert float to numeric values in 7.4.1 ,
> but i dont have a single clue...

There isn't a way to directly convert the type of a column in 7.4.x but 
you can duplicate the effect.

BEGIN;
ALTER TABLE fragment RENAME COLUMN x TO old_x;
ALTER TABLE fragment ADD COLUMN x numeric(10,2);
UPDATE fragment SET x = old_x;
ALTER TABLE fragment DROP COLUMN old_x;
COMMIT;

Make sure you check any functions/application code that might be 
expecting floating-point rather than numeric before you do this.

Oh, and upgrade from 7.4.1 to 7.4.7 as soon as possible.
--
   Richard Huxton
   Archonet Ltd