Re: Conditional rule?

On Thu, 27 Jul 2000, Robert B. Easter wrote:
> On Thu, 27 Jul 2000, Andr Nss wrote:
> > I've been looking through the material I have on postgreSQL, but can't seem
> > to find an answer to my problem. Very simplied, my tables are something like
> > this:
> >
> > create table news (
> > id serial,
> > story text,
> > publishtime timestamp
> > )
> >
> > create table news_unpublished (
> > news_id
> > )
> >
> > I wish to make rule looking something like this:
> > create rule newsrule as
> > on insert to news do
> > if new.publishtime is not null insert into news_unpublished
> > values(new.id);
> >
> > I.e. "On an insert to news, if new.publish is not null, insert the new
> > post's id into news_unpublished.
> >
> > Is this possible?
> >
> > Thanks
> >
> > Andr Nss
>

(forgot the BEGIN/END in the function!)

I think a PL/pgSQL trigger will work:

-- Load the PGSQL procedural language
-- This could also be done with the createlang script/program.
-- See man createlang.
CREATE FUNCTION plpgsql_call_handler()
RETURNS OPAQUE AS '/usr/local/pgsql/lib/plpgsql.so'
LANGUAGE 'C';
CREATE TRUSTED PROCEDURAL LANGUAGE 'plpgsql'
HANDLER plpgsql_call_handler
LANCOMPILER 'PL/pgSQL';

CREATE FUNCTION news_trigproc RETURNS OPAQUE AS '
BEGIN
IF TG_OP = ''INSERT'' THEN
-- unnessary IF above since this is always called on insert only
-- but shows how can detect which OP called the trigger when
-- you make a trigger handle more than just INSERT
IF NEW.publishtime NOTNULL THEN
INSERT INTO news_unpublished VALUES (NEW.id);
END IF;
RETURN NEW;
END IF;
END;
' LANGUAGE 'plpgsql';

CREATE TRIGGER newstrigger
AFTER INSERT ON news FOR EACH ROW
EXECUTE PROCEDURE news_trigproc();

--
- Robert