$dbh = DBI->connect(...);
sub foo { 
  $dbh->do(...);
}
$compartment = new Safe;
$compartment->share('&foo');
$compartment->reval('&foo();');

##</code><code>##

sub foo {
  my $dbh = DBI->connect(...); 
  $dbh->do(...);
  $dbh->disconnect();
}