From: Tim Landscheidt <tim@tim-landscheidt.de>
To: pgsql-sql@postgresql.org
Subject: Re: safely exchanging primary keys?
Date: Mon, 24 May 2010 14:38:39 +0000
Message-ID: <m3d3wl1i1c.fsf@passepartout.tim-landscheidt.de> (raw)
References: <20100524085101.GA21249@apartia.fr>
Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org> wrote:
> I have this function which swaps primary keys for cabin_types (so that
> id_cabin_type ordering reflects natural data ordering):
> CREATE OR REPLACE FUNCTION swap_cabin_types(id1 integer, id2 integer) RETURNS integer
> AS $$
> declare
> tmp integer;
> begin
> tmp := nextval('cabin_type_id_cabin_type_seq');
> update cabin_type set id_cabin_type=tmp where id_cabin_type=id1;
> update cabin_type set id_cabin_type=id1 where id_cabin_type=id2;
> update cabin_type set id_cabin_type=id2 where id_cabin_type=tmp;
> return tmp;
> end;
> $$
> LANGUAGE plpgsql;
> 'id_cabin_type' is a foreign key for two other tables, 'cabin_category'
> and 'alert_cabin_type', which have an "on update cascade" clause.
> When I run that function it seems the foreign keys are not properly
> updated and the data ends up in a mess.
> Did I forget something?
What does "are not properly updated" mean? Anyhow, why don't
you use something simple like (untested):
| UPDATE cabin_type
| SET id_cabin_type =
| CASE
| WHEN id_cabin_type = id1 THEN
| id2
| ELSE
| id1
| END
| WHERE id_cabin_type IN (id1, id2);
Tim
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: tim@tim-landscheidt.de
Subject: Re: safely exchanging primary keys?
In-Reply-To: <m3d3wl1i1c.fsf@passepartout.tim-landscheidt.de>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox