Thanks Bill,
Make sense... db_link is probably then solution... Everything depends on concrete problem...
But I still think security should be reconsidered (I would use db_link just in case there is no other options - if we must let users to have direct access to DB)... I mean, in that case when we need log each request for some sensitive data - we would not allow some user direct access to DB where he would be able to do such thing BEGIN TRAN, execute function what returns sensitive data, ROLLBACK Tran; (or many other things...)
at least there would be an application layer above DB... (concretly in our case - Users do not have access to DB at all... everything is through Web App, actually DB - Web Service - User Apps (Web, Windows, Mobile etc...))
Thanks,
Misa