From: | chester c young <chestercyoung(at)yahoo(dot)com> |
---|---|
To: | Luca Ferrari <fluca1978(at)infinito(dot)it> |
Cc: | sql pgsql <pgsql-sql(at)postgresql(dot)org> |
Subject: | Re: delete on cascade |
Date: | 2006-10-23 15:41:25 |
Message-ID: | 20061023154126.58178.qmail@web54307.mail.yahoo.com |
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Thread: | |
Lists: | pgsql-sql |
--- Luca Ferrari <fluca1978(at)infinito(dot)it> wrote:
> Hi all,
> I guess this is an already asked question, but I didn't found an
> answer, so
> apologize me. Imagine I've got two tables:
> skill(id,description) // primary key => id
> family(id,description) // primary key => id
> and I want to associate skills to families:
> ass_sf(id_skill,id_family) // appropriate foreign keys
>
> Tables are already created and the database is running. Now I'd like
> to
> implement a delete cascade, thus when I delete a skill also its
> association
> with the family must be deleted. I gues I should have declared the
> skill
> table as follows:
> CREATE TABLE skill
> (
> id varchar(20) on delete cascade,
> description varchar(50),
> primary key(id)
> );
>
> right? The problem is: how can I alter the table to add the column
> constraint
> now, without redeclaring the table?
> Thanks very much for helping me.
> Luca
drop the constraint and re-declare it. (you can see the constraint
name by \dt skill from psql.)
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