FOREIGN KEYs ... I think ...

I'm not sure if I'm looking at (for) the right thing or not, but if I am,
then I'm not finding any useful examples :(

I have two tables, simplified as:

CREATE TABLE incident_summary (
id serial,
subject text,
status boolean
);

CREATE TABLE incident_comments (
id serial,
incident_id int4,
body text,
comment_date timestamp,
status boolean
);

Now, what I want to do is add a FOREIGN KEY (again, I think) that when
incident_summary.status is changed (either closed, or reopened), the
associated records in incident_comments are changed to the same state ...

It *looks* like it should be simple enough, I want
incident_comments.status to change to incident_summary.status whenever
incident_summary.status changes ... since I'm finding nothing searching on
FOREIGN KEYS, I'm guessing that I'm looking at the wrong thing ...

So, what should I be searching on / reading for this one? Pointers
preferred, especially one with some good examples :)

Thanks ...

----
Marc G. Fournier Hub.Org Networking Services (http://www.hub.org)
Email: scrappy(at)hub(dot)org Yahoo!: yscrappy ICQ: 7615664