Re: Question on setting up trigger.

Saluton,

On Tue, Jan 02, 2001 at 09:38:52AM -0700, Alan Young wrote:
> I have the following table:
>
> CREATE TABLE category (
>         id int NOT NULL DEFAULT nextval('_base_id_seq'::text) PRIMARY
> KEY,
>         parentid int REFERENCES category ( id )
>         name text,
> );
>
...
> CREATE FUNCTION "move_catparent" (int4 )
> RETURNS int4
> AS 'UPDATE category
>     SET parentid = ( SELECT parentid FROM category WHERE id = $1 )
>     WHERE parentid = $1;
>     SELECT 1 AS RESULT'
> LANGUAGE 'SQL';

I myself don't know much about triggers, but I think you need:

create trigger <trigger name> before delete on category
  for each row execute procedure move_catparent(old.id);

On the other hand, I suppose that a rule might be the better option.

I don't know much about this, so don't take this at face value.

Albert.


>
> As it stands, I have to do the following when deleting a category:
>
> SELECT move_catparent( <id of category being deleted> );
> DELETE FROM category WHERE id=<id of category being deleted>;
>
...

--

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Albert Reiner                                   <areiner@tph.tuwien.ac.at>
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