This works for me:

use DBI;

my $dbh = DBI->connect("dbi:SQLite:dbname=count.db","","");

my $sth1 = $dbh->prepare('select id from threads');
my $sth2 = $dbh->prepare('select count(*) from replies where thid = ?'
+);

$sth1->execute;

for my $thid ( @{$sth1->fetchall_arrayref} )
{
    print "Thread: ", $thid->[0], "...\n";
    $sth2->execute($thid->[0]);
    print "Replies for thread ", $thid->[0], ": ", $sth2->fetchrow_arr
+ay, "\n";
}

$sth1->finish;
$sth2->finish;
$dbh->disconnect;

__END__

SQL Schema:
sqlite> create table threads ( id integer primary key, title varchar(2
+56) );
sqlite> create table replies ( id integer primary key, thid integer, t
+itle varchar(256) );
sqlite> insert into replies values (1, 1, 're: test1' );
sqlite> insert into replies values (2, 1, 're: re: test1' );
sqlite> insert into replies values (3, 2, 're: test2' );
sqlite> insert into threads values (1, 'test1');
sqlite> insert into threads values (2, 'test2');

Execution:
$ perl test_count.pl
Thread: 1...
Replies for thread 1: 2
Thread: 2...
Replies for thread 2: 1
$
[download]

Maybe your setup is different, but you should be able to translate appropriately...

Best regards...

This is the closest to what I was actually thinking of doing out of these threads...I'm sure faster than what I have posted as well

meh.