#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my @employees = ( 
    { FIRST => 'Bill',   LAST => 'Gates',     
      SALARY => 600000, AGE => 45 },
    { FIRST => 'George', LAST => 'Tester',
      SALARY =>  55000, AGE => 29 },
    { FIRST => 'Sally',  LAST => 'Developer', 
      SALARY =>  55000, AGE => 29 },
    { FIRST => 'Joe',    LAST => 'Tester',    
      SALARY =>  55000, AGE => 29 },
    { FIRST => 'Steve',  LAST => 'Ballmer',   
      SALARY => 600000, AGE => 41 } 
);

sub cmp_by {
    my $result = 0;
    for my $term (@_) {
        $result ||= $a->{$term} cmp $b->{$term};
    }
    return $result;
}

print Dumper sort {cmp_by(qw(LAST FIRST))} @employees;