...
my @fields = qw( SamAccountName ExpiryDate PasswordLastSet mail );
my $format = "%-25s %-25s %-25s %-25s\n";

# header fields
printf $format, @fields;
# underline header fields (same length as header fields
printf $format, map { '-' x length $_ }  @fields;


my $datasets = get_datasets( $handle );
for my $set ( @$datasets ) {
  my %h = %$set;
  printf $format, @h{@fields};
}