#!/usr/local/bin/perl -w

use strict;

my $data = (
    [
        {
            num     => 'OF1234',
            title   => 'title OF1234',
        },
        {
            num     => 'AF1234',
            title   => 'title AF1234',
        },
        {
            num     => 'AF1234',
            title   => 'title AF1234',
        },
    ]
);

#print @{$data};

my @sorted =
                # now get the original array ref back
    map { $_->[0] }
                # use field 1 of anonymous array to sort (in this
                # case num)
    sort { $a->[1] cmp $b->[1] }
                # make an anonymous array of itself and num
    map { [$_, $_->{num}] }
                # start with the array ref and make it an array
    @{$data};
print join ', ', map { $_->{num} } @sorted;
print "\n";

my %saw;
undef %saw;

my @unique = grep !$saw{$_->{num}}++, @sorted;
print join ', ', map { $_->{num} } @unique;

print "\n";
exit;

##</code><code>##

AF1234, AF1234, OF1234
AF1234, OF1234

##</code><code>##

my @keys = sort keys %{ { map { $_ => 1 } @array1 } };