Excellent, thank you!
Before I got this, here is what I came up with.
Please tell me what you think.

The reason I would like it to stay in the database, is because I am making an Admin interface for our company, where we can add new names delete them, and do a ton of other things not related to the forbidden names, such as manage the registered users, change our hosting packages, domain prices and all that.

So here is what I came up with...

    my $is_bad = 0;
    $sth = $dbh->prepare (qq{ SELECT * FROM `forbidden_usernames` });
    $sth->execute();
    while($row = $sth->fetchrow_hashref()) {
        if ($row->{f_user} =~ m/$str/i || $str =~ m/$row->{f_user}/i) 
+{
            $is_bad++;
            last;
        }
    }
    $sth->finish();

if ($is_bad != 0) {
    return("bad");
}
[download]

That checks it both ways.

I have not yet tested it. But what do you think, would it work about like yours does?

Thank you!!

Richard.