Hi, group. I erroneously posted message on that subject to
*firebird-devel* as possible bug and now, having made more experiments,
suspect that it is not a bug but feature and move discussion here.
Essence: FB (don't know about IB) checks priveleges even if no actions
are really performed.
Details: I have a trigger on one table and in case of some condition
it can access another table. When this trigger fires for user that have
no rights on second table, even if condition is'nt satisfied and no
access performed, exception -551 raises.
I encountered it accidentatlly in develop time, and it is not problem
to manage priviliges to real work time. I was surprized by principle.
How far it is from "this user can't access this table because he cannot
access referenced table" or even "this user cannot access database
because he cannot access one table within it"?

Best regards.