OID use

Here is essentially what I am trying to do:

I want to have a 'serial' type column, so that it provides a unique
identifier for records. However, when I do the insert, I need the know
what value was assigned to that so I can use it in another table for
reference, by doing another insert.

I looked at the C API and found a function 'PQoidValue' which returns an
Oid. I tried to find a place to use the Oid type, but could not. Is
there a more efficient way of getting record information than executing
a 'select * where ... oid=...'? And what restrictions should I be aware
of when working with Oids?

Regards,
Jeff Davis