Re: self-referential UPDATE problem on 7.4

Karsten Hilbert <Karsten.Hilbert@gmx.net> writes:
> I am trying to run this query in psql:

> update clin.episode
> set fk_patient = clin.health_issue.fk_patient
> from clin.health_issue
> where
>     clin.episode.fk_patient is NULL and
>     clin.episode.fk_health_issue = clin.health_issue.pk;

> It returns "UPDATE 2" which is what I expect from the data.
> However, the rows in question are not actually updated.

That seems very strange.  Could you perhaps have a BEFORE UPDATE trigger
that's changing the values back to null again?

            regards, tom lane