prepare("SELECT * FROM messages WHERE (sender_id = :sender_id AND receiver_id = :receiver_id) OR (sender_id = :receiver_id AND receiver_id = :sender_id) ORDER BY sent_at ASC"); $stmt->execute([ ':sender_id' => $sender_id, ':receiver_id' => $receiver_id ]); $messages = $stmt->fetchAll(PDO::FETCH_ASSOC); $stmt3324 = $pdo->prepare("SELECT * FROM users WHERE id = :user_id"); $stmt3324->execute([':user_id' => $receiver_id]); $receiver = $stmt3324->fetch(PDO::FETCH_ASSOC); ?>