3.5 Configure Data Access Control
Define data grants to control which rows and columns each end user can
access. In data grant predicates, ORA_END_USER_CONTEXT.username returns the
end user's name from the current end-user security context.
Note:
To queryORA_END_USER_CONTEXT directly or to use it in data grant
predicates, you must set the database instance's COMPATIBLE
initialization parameter to 20.0 or greater.