create role business_user_role;
grant select on app_schema.table_a to business_user_role;
grant select on app_schema.table_b to business_user_role;
--
grant business_user_role to bob;
grant business_user_role to carol;
grant business_user_role to ted;
grant business_user_role to alice;

create table app_schema.table_c
   (col_a varchar2(10)
    );
grant select on table app_schema.table_c to business_user_role;