eval {
    my $sth = $dbh -> prepare (<<'    --');
               update  new_table 
                  set  newData = ? 
                where  newID   = ?
    --
    while (my ($id, $data) = each %Data) {
        $sth -> execute ($data, $id)
    }
};
if ($@) {
    $dbh -> rollback;
    die $@;
}
else {
    $dbh -> commit;
}