About selecting rows

Hello,
I've a table "users" with columns id, login and sec_level, where the latter
contains an integer 1..3.
Each db user logs in with his username. Till today I left access to the
record (of another table "works") that had, in the column "requested_by",
the same name of the current db user, with

select id, id from works where requested_by = ".get_session("UserID")."
order by id desc

Now I'd like that users with sec_level 2 and 3 can access to all records in
works table. Can I do it with an unique instruction inserting Case.. when
controls? And how?.

Thanks a lot
A.