# Gives:
#    key1,field1,field2,field3,field4
#    key1,field1,field2,field3,field4
#    key1,field1,field2,field3,field4
#    key2,field1,field2,field3,field4
#    key3,field1,field2,field3,field4
#    key3,field1,field2,field3,field4
#
# Doesn't handle commas in key or field.

$,=',';
$\=$/;
foreach $key (keys(%db)) {
   foreach $record (@{$db{$key}}) {
      print $key, @$record;
   }
}

-or-

# Gives:
#    key1,0,field1,field2,field3,field4
#    key1,1,field1,field2,field3,field4
#    key1,2,field1,field2,field3,field4
#    key2,0,field1,field2,field3,field4
#    key3,0,field1,field2,field3,field4
#    key3,1,field1,field2,field3,field4
#
# Doesn't handle commas in key or field.

$,=',';
$\=$/;
foreach $key (keys(%db)) {
   for ($record_num=0; $record_num<@{$db{$key}}; $record_num++) {
      print $key, $record_num, @{$db{$key}[$record_num]};
   }
}