SELECT
p.product_id,
ifnull(
count(dp.post_id),
0
) as discussion_amount_posts
FROM
q_discussion
INNER JOIN q_products as p ON (
q_discussion.object_id = p.product_id
)
INNER JOIN q_discussion_posts as dp ON (
q_discussion.thread_id = dp.thread_id
AND q_discussion.object_type = 'P'
)
WHERE
dp.status = 'A'
and p.product_id in (45805)
GROUP BY
p.product_id