{
   'code' => 'YYK',
   'expdate' => '2017-01-01', # <<< noticed that this value was found in the hashref XXY
   'date' => '2014-02-20',
   'product' => 'buc',
   'city' => 'MARS'
 }

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

 my $data = [
 {
   'code' => 'XXY',
   'expdate' => '2017-01-01',
   'date' => '2017-01-30',
   'product' => 'cell',
   'city' => 'NYK'
 },
 {
   'code' => 'YYK',
   'expdate' => '2015-05-05',
   'date' => '2014-02-20',
   'product' => 'buc',
   'city' => 'MARS'
 },
 {
   'code' => 'RX Issued',
   'expdate' => '2019-11-09',
   'date' => '2011-03-11',
   'product' => 'idx',
   'city' => 'BXO'
 },
];


my $results = process( $data );

print "\n\n";
print Dumper $results;
print "\n\n";
   
sub process {

  my $all = shift || return;
  
  my $setdate;
  my $newdate;

  foreach my $all_item (reverse @{ $all }) {

    # If XXY is found use the value in the "expdate" to replace the "expdate" value in YYK
    
    # First check if XXY is true and store it
    if ( $all_item->{ code } eq 'XXY' ) {

      $newdate = $all_item->{expdate};
      
    } 

    if( $all_item->{ code } eq 'YYK') {

      # Now, set the new date
      $all_item->{expdate} = $newdate if $newdate;
      
      $setdate = $all_item;
      
    }

  }

  return $setdate;
  
}