SELECT
    COUNT(*) AS hoeveelheid_berichten,
    twitter_id,
    firstname,
    name
FROM
    backend_tweet T,
    backend_person P,
    backend_feed F,
    backend_organization O,
    backend_person_organizations PO
WHERE
    T.twitter_id = F.id
    AND
    F.actor_id = P.actor_ptr_id
    AND
    P.actor_ptr_id = PO.person_id
    AND
    O.actor_ptr_id = PO.organization_id
    AND
    in_reply_to_user_id IS NULL
    AND
    retweeted_user_id IS NULL
GROUP BY
    firstname
ORDER BY
    hoeveelheid_berichten
    DESC