I have a problem setting up a VIEW to behave like I want it to.

There is a base table PERSON where all data is stored.
And there are several groups of persons that I want to treat separately
and that I want to treat through VIEWs, such as AUTHOR, HIST_PERSON,
COMPOSER a.s.o. For this I have a flag field in the base table called
AUTHOR_FL...

When creating the SELECT statement for the views I include a clause like
'WHERE AUTHOR_FL = 1' and it selects the right rows.
I would however prefer not to have this flag field in the VIEW at all
(so no user can mess with it) but to set it directly with the VIEW.

Now the problem is: if the flag field is not in the VIEW declaration,
(how) can I tell a TRIGGER to set this field in the underlying base table?

What is the appropriate approach to this.
It would be easy if the flag field shows also in the VIEW, but as
mentioned I would prefer not to do this.

Any help would be appreciated
Thanks a lot
Urs