SQL Query for number of posts per user group

[Dave]

Try:

SELECT COUNT(*) AS posts, post.userid
FROM post
LEFT JOIN user ON post.userid = user.userid
WHERE user.usergroupid IN (10, 62) 
AND visible = 1
AND dateline BETWEEN UNIX_TIMESTAMP( '2015-06-30') AND UNIX_TIMESTAMP( '2015-10-01') 
GROUP BY post.userid
ORDER BY posts DESC