Re: Triggers and SQL functions

pierre@desertmoon.com wrote:
>
> >
> > I have exactly the same problem as you mentioned in a mail
> > sent to postgres mailing lists about creating trigger using
> > sql function ...
> >
> > Did you get the solution to you problem ?
> >
> > Ph.R.
> >
> >
>
> I actually found the solution in the docs. The solution is to understand
> the difference between triggers and rules. Triggers are used primarily
> to call C/C++ library functions that you can create and add onto the
> postgresql system.
>
> Rules on the other-hand act just like 'triggers' but only call/usr
> sql to perform their functions.
>
> So the solution: Use rules to create trigger-like actions that run
> stored sql procedures. There is a man page on 'create rule' that you
> can use to get more info.
>
> -=pierre
I found out the following trick ... but I m not sure it s clean !

-- Makes all user at least belonging to Void ... just in case
CREATE FUNCTION adduservoid () returns boolean
 as 'insert into user_realm
        select id as uid,1 as rlid,false as adminuser
        from user where not exists (
           select uid from user_realm where user.id=user_realm.uid
        );
     select true as ignore_this;'
 language 'sql';
CREATE RULE autoadduservoid as
    on insert to user
    do select adduservoid();

Ph.R.

--
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Philippe Rochat,                EPFL   DI-LBD
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