I'm the author of DBIx::Tree:NestedSet. Out of the box it supports SQLite and MySQL, I'm looking for more database champions to beef up support.

Below is one way you could set up your tree. I did it manually for the sake of verbosity.

Note: I'm about to release a new version of the module (it's currently at 0.12), the most glaring bug it fixes is the broken return value of the various add_* methods.

This module is pretty young, caveat coder. I'm very open to patches and bug fixes, (this module is important to a few apps I've got out there) I won't be abandoning it anytime soon.

#!/usr/bin/perl
use DBI;
use DBIx::Tree::NestedSet;
use Data::Dumper;
use strict;

my $dbh=DBI->connect('dbi:SQLite:dbname=nested_set') or die($DBI::errs
+tr);


my $tree=DBIx::Tree::NestedSet->new(dbh=>$dbh,db_type=>'SQLite');

$tree->create_default_table();

$tree->add_child_to_right(term=>'Body Regions');
$tree->add_child_to_right(
              term=>'Extremities',
              id=>$tree->get_root()
             );

my $extremities_id=$tree->get_id_by_key(
                    key_name=>'term',
                    key_value=>'Extremities'
                       );
foreach('Arm','Elbow','Hand'){
    $tree->add_child_to_right(
                  term=>$_,
                  id=>$extremities_id
                 );
}

my $hand_id=$tree->get_id_by_key(
                 key_name=>'term',
                 key_value=>'Hand'
                );
$tree->add_child_to_right(
              id=>$hand_id,
              term=>'Fingers'
             );

my $fingers_id=$tree->get_id_by_key(
                    key_name=>'term',
                    key_value=>'Fingers'
                   );

$tree->add_child_to_right(
              id=>$fingers_id,
              term=>'Thumbs'
             );

my $structure=$tree->get_self_and_children_flat();

foreach(@$structure){
    print " " x $_->{level}. $_->{term}."\n";
}

$dbh->do('drop table nested_set');
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