Código PHP:
$threads = $database->get_all(
"SELECT f.id, f.title, f.date, p.date, u.name AS user_name, u.email AS user_email, sum(1) - 1 AS response_count ".
"FROM forum_threads AS f ".
"INNER JOIN users AS u ".
"ON f.user_id = u.id ".
"INNER JOIN forum_posts AS p ".
"ON p.thread_id = f.id ".
"GROUP BY f.id, f.title, f.date, u.name, u.email ".
"ORDER BY p.date DESC LIMIT ?, ?"
, array($pageNumber * $threadsPerPage, $threadsPerPage)
);