Re: Rows are repeating by the trigger function

Hi Alban,

I agree with you about the UPDATE.
Thanks for pointing out.

regards
Kiran

On Sun, Oct 30, 2016 at 12:49 PM, Alban Hertroys <haramrae(at)gmail(dot)com> wrote:

>
> > On 30 Oct 2016, at 10:31, Kiran <bangalore(dot)kiran(at)gmail(dot)com> wrote:
> >
> > Dear Folks,
> >
> > I have a table cf_question with 31 rows.
> > I want to insert/update another table cf_user_question_link when
> cf_question table is inserted/updated with row(s).
> > I have written trigger function for this as follows.
> >
> >
> > CREATE FUNCTION user_question_link() RETURNS trigger AS
> > $user_question_link$
> > begin
> > SET search_path TO monolith;
> > INSERT INTO
> > cf_user_question_link(cf_user_id,cf_question_id)
> > VALUES(NEW.user_id,NEW.cf_question_id);
> > RETURN NEW;
> > end;
> > $user_question_link$
> > LANGUAGE plpgsql
> > COST 100;
> >
> >
> > /* Call the trigger function */
> >
> > CREATE TRIGGER insert_user_question_link AFTER INSERT OR UPDATE
> > ON monolith.cf_question
> > FOR EACH ROW EXECUTE PROCEDURE user_question_link();
> >
> >
> > Problem: The cf_user_question_link gets inserted with 94 rows instead of
> 31 rows. The 31 rows are repeated 3 times
> > I tried dropping the trigger function and recreating it
> but with the same 94 rows in the table.
> >
> > It would be great if any from the forum point to me where I am doing
> wrong.
>
> I don't think you want that same trigger to fire on UPDATE of cf_question,
> like you do now.
>
> On UPDATE you have two choices;
> - either you need to take changes to those _id columns into account and
> delete rows that belong to the OLD link and not to the NEW one (or do
> nothing if those stayed the same)
> - or you do nothing (no trigger needed) because in the majority of cases
> changing FK's is limited to a few power users at best and they're supposed
> to know what they're doing.
>
> Alban Hertroys
> --
> If you can't see the forest for the trees,
> cut the trees and you'll find there is no forest.
>
>