# print the beginning of the select
print "<select name='categories' SIZE='5'>\n";

# select top-level elements, and specify top level
recurQuery(0,0);

# my super recurse the tree function, takes 2 options being parentid, and current level
sub recurQuery {
        my $parentId=$_[0];
        my $level=$_[1];
        my $data = "SELECT id, parentid, catname from categories WHERE parentid = $parentId";
        my $sth = $dbh->prepare($data);
        $sth->execute() or die $dbh->errstr;

        # loop through results
        while (my @results = $sth->fetchrow_array) {
                
                # print the beginning of the option box
                print"<option name='$results[2]'>";
                
                # loop based on level, for indentation
                for (my $i = 0; $i < $level; $i++) {
                        print "&nbsp;*";
                }
                
                # print end of option box
                print $results[2]."</option>\n";
                
                # find child elements of this one
                my $data = "SELECT id, parentid, catname from categories WHERE parentid = $results[0]";
                my $sth = $dbh->prepare($data);
                $sth->execute() or $dbh->errstr;
                
                # get number of rows returned
                my $rownumbersub = $sth->rows;
                
                # if rows returned, exec this
                if($rownumbersub > 0) {
                        
                        # loop through children
                        while (my @resultssub = $sth->fetchrow_array) {
                                
                                # re-exec this function with the child ID and new level
                                recurQuery($resultssub[1],$level+1);
                        }
                }
        }
}

# close that thar select box