use Some_DB_that_you_like;
tie %db Some_DB_etc;

my $two_level_hash = $what_ever_your_data;

for my $key_one (keys %$two_level_hash){
   my @vals = values %{ $two_level_hash->{$key_one} };
   my $item = join '|', @vals;
   $db{ $key_one } = $item;
}