Question

i have users table and i have posts table i want select from users the top users that have the big amount of posts from posts table and order them by numbers of posts
i can make it by array_count_values() by i cant order it
now i think if i make it by one mysql query by left and join will be more better

table structure

posts

id | auther_id

i tried this

SELECT COUNT(1) cnt, u.user_id 
FROM users u 
LEFT JOIN posts p
ON p.author_id=u.user_id
GROUP BY u.user_id
ORDER BY cnt DESC
LIMIT 20

---

it gave me this
alt text http://img511.imageshack.us/img511/6707/31154352.gif
see the arrow
what is this
i just have 2 posts under user_id 5
what is this first row

Answer 1

You need to aggregate the posts by user using GROUP BY u.user_id, get a COUNT value for the number of posts and ORDER BY that number, in descending order:

SELECT COUNT(1) cnt, u.user_id 
FROM users u 
LEFT JOIN posts p
ON p.author_id=u.user_id
GROUP BY u.user_id
ORDER BY cnt DESC
LIMIT 20