triggering on deletes, NEW row or OLD row?

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi folks,

I hope this question isn't a stupid one, but I'm fairly much a newbie to
SQL in general and Postgres in particular.

I have a table (abbreviated for clarity sake) that contains:

create table change_record (
change_record_id integer not null
default nextval('change_record_id_seq')
primary key,
--- Some other fields
associated_with_project boolean not null default 'false'
);

and a second table such that:

create change_record_map (
change_record_map_id integer not null
default nextval('change_record_map_id_seq')
primary key,
change_record_id integer not null
references change_record(change_record_id)
on delete cascade,
project_id integer not null
references projects(project_id)
on delete cascade
);

What I want to put into my schema is two triggers. One for when a row
is added to the change_record_map it forces the column in the
change_record table "associated_with_project" to be set to true
appropriately. That part I have down OK.

The other trigger I want to put in place is when a delete happens to a
record in the table change_record_map I check to make sure that the
associated change record is not associated with another project (could
happen) and force the associated_with_project column in the
change_record table to false ONLY if there are no other associated
projects.

The question I have is with a trigger on delete are the NEW and OLD
system variables valid? Which one is valid?

- --
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Peter L. Berghold Peter(at)Berghold(dot)Net
"Those who fail to learn from history are condemned to repeat it."
AIM: redcowdawg Yahoo IM: blue_cowdawg ICQ: 11455958
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.3 (GNU/Linux)
Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org

iD8DBQFDnwE9UM9/01RIhaARAtSAAJ9JeRDrUQr0LI8965+Mgs7DmS/wOACeIWTU
SBhMrFAAlEvE2qdgFOk81tk=
=WrRq
-----END PGP SIGNATURE-----