Re: conditional rule not applied

On Wed, 30 Dec 2009 20:04:51 -0600,
Seb <spluque(at)gmail(dot)com> wrote:

> On Wed, 30 Dec 2009 19:39:15 -0600,
> Seb <spluque(at)gmail(dot)com> wrote:

> CREATE RULE footwear_nothing_upd AS
>> ON UPDATE TO footwear DO INSTEAD NOTHING; CREATE RULE
>> footwear_newshoelaces_upd AS ON UPDATE TO footwear WHERE NEW.sl_name
>> <> OLD.sl_name AND OLD.sl_name IS NULL DO INSERT INTO shoelaces
>> (sh_id, sl_name) VALUES(NEW.sh_id, NEW.sl_name);

> I think my error is in the test expression, which doesn't deal
> properly with the null value, so correcting:

> CREATE RULE footwear_nothing_upd AS
> ON UPDATE TO footwear DO INSTEAD NOTHING;
> CREATE RULE footwear_newshoelaces_upd AS
> ON UPDATE TO footwear
> WHERE NEW.sl_name IS DISTINCT FROM OLD.sl_name AND OLD.sl_name IS NULL
> DO
> INSERT INTO shoelaces (sh_id, sl_name)
> VALUES(NEW.sh_id, NEW.sl_name);

> However, could a more direct and robust test for an inexistent record
> in 'shoelaces' be made?

Any ideas? I'm not sure this is the best way to test whether the record
to update corresponds to a inexistent record in 'shoelaces'. Thanks.

--
Seb