Re: Conditional rule?

On Thu, 27 Jul 2000, Andr� N�ss 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� N�ss

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_handlerLANCOMPILER 'PL/pgSQL';

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

CREATE TRIGGER newstriggerAFTER INSERT ON news FOR EACH ROWEXECUTE PROCEDURE news_trigproc();

--         - Robert