The default "do" method is logically similar to:

  sub do
  {
      my ($dbh, $statement, $attr, @bind_values) = @_;
      my $sth = $dbh->prepare ($statement, $attr) or return undef;
      $sth->execute (@bind_values) or return undef;
      my $rows = $sth->rows;
      ($rows == 0) ? "0E0" : $rows; # always return true if no error
      } # do