package mydbh;
@ISA = qw( DBI );
require DBI;
use strict;
sub new {
   my( $class, $dns, $username, $password ) = @_;
   my $self = DBI->connect( $dns, $username, $password );
   push (@ISA, ref($self))
     if (not grep { $_ eq ref($self) } @ISA);
   return bless $self, $class;
}