users, address record restrictions

I've got an interesting problem - this MIGHT (probably) isn't the right
forum for this. (pointed here from "interfaces")

however - I'd like to restrict access to specific records and groups of
records (based on another table) - and I'm not even sure where to start
looking. I suspect I actually need to look into triggers and/or
embedded libraries to solve this (and this means writing it) but I
haven't figured where to start...

basically per-record (given a set of rules) access restrictions.

Please do let me know where I can ask more :)

Looking for controlling SELECT, INSERT, UPDATE and DELETE. I -am-
interested in examples of server-side scripting as well... am still
searching.

Ta!
- Teunis Peters