unfortunately I cannot tell to what end, it might be 3 levels deep or more so I don't want to hard code it.

I actually have these info in a mysql db, what I would want to do is pulling those data, build the hash so I can display them in a nicely formatted structure.

root
  - first level
  -- second level
  --- third level
  - first
[download]

and so on, I am using Template Toolkit and I figured out that I can display it this way using "VIEWS" but I have no idea how to sort up this mess.

Note that both the 'id' & 'name' fields are important (the name so a user can understand what this section is and the ID for editing it)

I know nothing about TT and having glanced at the documentation I really don't want to get up to speed with it for this exercise. However the following may get you headed in a useful direction:

use strict;
use warnings;
use DBI;

my $tmpFileName = 'temp';
open my $outFile, '>', $tmpFileName or die "Can't open $tmpFileName: $
+!\n";
print $outFile $_ for <DATA>;
close $outFile;

my $dbh = DBI->connect ("DBI:CSV:")
    or die "DBI connect failed: $DBI::errstr";
my $sth = $dbh->prepare ("SELECT * FROM temp");
my @structure;
my %idMap;

$sth->execute ();
while (my $row = $sth->fetchrow_hashref) {
    my ($id, $name, $parent) = @{$row}{'id', 'name', 'parent'};

    if (! $parent) {
        push @structure, {id => $id, name => $name, children => []};
        $idMap{$id} = $structure[-1];
        next;
    }

    if (exists $idMap{$parent}) {
        push @{$idMap{$parent}{children}}, {id => $id, name => $name, 
+children => []};
        $idMap{$id} = $idMap{$parent}{children}[-1];
        next;
    }

    die "Can't handle children id provided before parent";
}
$sth->finish     ();
$dbh->disconnect ();

print dumpChildren($_) for @structure;


sub dumpChildren {
    my ($node, $indent) = @_;

    $indent ||= '';

    my $str = "$indent$node->{name}\n";

    $indent .= '   ';
    $str .= dumpChildren ($_, $indent) for @{$node->{children}};
    return $str;
}


__DATA__
id,name,parent
1,data1,0
2,data2,1
3,data3,1
4,data4,3
5,data5,4
[download]

Prints:

data1
   data2
   data3
      data4
         data5
[download]

---

True laziness is hard work