$dbh->{AutoCommit} = 0; 
  $dbh->{RaiseError} = 1;

  my $id = 737;

  my $rows;
  if (!eval {
      my $sql = "UPDATE stockhistory SET invoiced = 1 WHERE id = ?";
      my $sth = $dbh->prepare($sql);
      $rows = $sth->execute($id);
      $dbh->commit();
      1
  }) {
      print "Transaction aborted because $@";
      $dbh->rollback();
  }

  die("Record $id not found") if $rows < 1;
[download]

Note: Can't check if $rows is true since "0E0" (equal to zero but true) is returned when no rows are affected.

Thanks for all your help monks.
I'll re-write my script to include your suggestions.

Exactly.

Your query might successfully update every record in the table, or only one, or none at all, but it ran successfully. The number of rows affected is provided by:

print 'The query updated '. $sth->rows . " rows.\n";
[download]