Hash of hashes syntax

[jens]

I'm doing a bit of data munging for a client and
I want to suck around 6,000 records from a flat file
into a large hash of hashes. I've RTFM'd and I'm still
struggling--your help would be much appreciated.

Here's what I have so far:

my %hash_of_hashes = ( my $record_no => my %unitfiles_hash );

#suck all the unit files into a big hash to make searching easier
while (<UNITFILES>) {

    my @unitfiles_field = split /,/;

    #this is just an autogen number
    $record = $unitfiles_field[0];

    %hash_of_hashes{$record_no} = (

      %unitfiles_hash = ( 
         lastname         => $unitfiles_field[1],
         firstname        => $unitfiles_field[2],
         DOB              => $unitfiles_field[7],
         funding          => $unitfiles_field[18],
         URNo             => $unitfiles_field[15],
         Photo_permission => $unitfiles_field[14],
                        );
      );
} #end while

I've also considered using an array of hashes, but that's also confused me.
Please help!
--
Microsoft delendum est.