I agree with Generoso: use SQL when possible.

P.S. Here's your structure: 
use warnings;
use strict;
use Data::Dump qw(pp);

my %hash;
while (<DATA>) {
    chomp;
    next if /\A\s*\z/;
    my @pieces = split ',' => $_;
    for my $idx (3..4) {
        push @{
            $hash
            {$pieces[0]}
            {$pieces[1]}
            {$pieces[2]}
            [$idx-3]
        }, $pieces[$idx];
    }    
}
pp %hash;

__DATA__
Joe,A,1,85,90
Joe,A,1,80,99
Joe,A,2,50,70
Joe,A,2,60,65
Joe,A,2,87,89
Joe,B,1,82,92
Joe,B,3,30,51
Rob,A,1,64,77
Rob,B,2,20,32

[download]
(
  "Joe",
  {
    A => { 1 => [[85, 80], [90, 99]], 2 => [[50, 60, 87], [70, 65, 89]
+] },
    B => { 1 => [[82], [92]], 3 => [[30], [51]] },
  },
  "Rob",
  { A => { 1 => [[64], [77]] }, B => { 2 => [[20], [32]] } },
)

[download]

In reply to Re: hoh or hoa data structure by eff_i_g
in thread hoh or hoa data structure by rocky13

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