use CGI::Request;
my $req = new CGI::Request;
my $rows_per_page = 100;
my ($first_row, $command) = map { $req->param($_) } 
                                qw/first_row command/;
if ($command eq 'previous_page') {
  $first_row -= $rows_per_page;
  $first_row = 0 if $first_row < 0;
} elsif ($command eq 'next_page') {
  $first_row += $rows_per_page;
}

my $result = Database->get_results($query, $first_row);
Display->results($result, $first_row);