EG/DB.pm
EG/DB/
EG/DB/Access.pm
EG/DB/Clients.pm
EG/DB/Vendors.pm
EG/DB/Employees.pm
EG/Example.pm

##</code><code>##

package EG::DB.pm;
 use DBI;
 sub new { db connection happens here }
 sub commit {...}

package EG::DB::Access.pm
  use base 'EG::DB::Clients';
  use base 'EG::DB::Vendors';
  use base 'EG::DB::Employees';

package EG::DB::Clients;
  use base 'EG::DB';
  sub get_client_id_for_username { ... }

package EG::Example;
  use EG::DB::Access;
  my $dbh        = EG::DB::Access->new();
  my $client_id  = $dbh->get_client_id_for_username($client_username);

##</code><code>##

EG::Example->get_client_id_for_username()

##</code><code>##

       EG::DB::Access   (no match) 
       EG::DB::Clients  (no match) 
       EG::DB::Vendors  (no match) 
       EG::DB::Employee (match)

##</code><code>##

       EG::DB::Access   (no match) 
       EG::DB::Clients  (no match) 
       EG::DB::Vendors  (no match) 
       EG::DB::Employee (no match) 
       EG::DB           (match)