Restrict access to certain tables for users who have DBA roles

List all users who have been assigned a particular role

-- Change 'DBA' to the required role
select * from dba_role_privs where granted_role = 'DBA'

List all roles given to a user

-- Change 'PHIL@ to the required user
select * from dba_role_privs where grantee = 'PHIL';

List all privileges given to a user

select
  lpad(' ', 2*level) || granted_role "User, his roles and privileges"
from
  (
  /* THE USERS */
    select 
      null     grantee, 
      username granted_role
    from 
      dba_users
    where
      username like upper('%&enter_username%')
  /* THE ROLES TO ROLES RELATIONS */ 
  union
    select 
      grantee,
      granted_role
    from
      dba_role_privs
  /* THE ROLES TO PRIVILEGE RELATIONS */ 
  union
    select
      grantee,
      privilege
    from
      dba_sys_privs
  )
start with grantee is null
connect by grantee = prior granted_role;

Note: Taken from http://www.adp-gmbh.ch/ora/misc/recursively_list_privilege.html

List which tables a certain role gives SELECT access to?

-- Change 'DBA' to the required role.
select * from role_tab_privs where role='DBA' and privilege = 'SELECT';

List all tables a user can SELECT from?

--Change 'PHIL' to the required user
select * from dba_tab_privs where GRANTEE ='PHIL' and privilege = 'SELECT';

List all users who can SELECT on a particular table (either through being given a relevant role or through a direct grant (ie grant select on atable to joe))? The result of this query should also show through which role the user has this access or whether it was a direct grant.

-- Change 'TABLENAME' below
select Grantee,'Granted Through Role' as Grant_Type, role, table_name
from role_tab_privs rtp, dba_role_privs drp
where rtp.role = drp.granted_role
and table_name = 'TABLENAME' 
union
select Grantee,'Direct Grant' as Grant_type, null as role, table_name
from dba_tab_privs
where table_name = 'TABLENAME' ;

IMO, an external table is much easier to manage and flexible than a SQLLoader script. So if you're already doing a recurring SQLLoader load, I see no possibilities of evil in switching to external tables.

By doing the external table, even though the base of the table resides in a text file outside the database, the data can be accessed from within the database, no need for a separate SQLLoader tool/scripts. So you can write procedures/packages to manipulate the data straight from the external table. No need to load it anywhere...as long as it's in the directory you have set, it's already "loaded".

As a DBA, I'd much prefer managing a DML script using an external table than having to manage a SQLLoader script. But SQLLoader has been around a while....if your DBA has too, it may be a tough sell. :)