#!/usr/bin/perl -w

use strict;
use Data::Dumper;

my %hash;

while (<DATA>) {
    chomp;
    my @row = split(':');
    $hash{$row[2]}->{$row[1]} = 1;
}

print Dumper( \%hash ) . "\n";

__DATA__
D1:111:92111
D2:112:92111
D3:111:92111
D4:112:92111
D5:111:90222
D6:112:90222
D7:111:90222
D8:112:90222