solution.sql

SELECT
	users.user_id,
	COALESCE(post_count, 0) AS post_count,
	COALESCE(page_count, 0) AS page_count
FROM users
LEFT JOIN (
	SELECT user_id, COUNT(*) AS post_count
	FROM posts
	GROUP BY user_id
) post_counts ON post_counts.user_id = users.user_id
LEFT JOIN (
	SELECT user_id, COUNT(*) AS page_count
	FROM pages
	GROUP BY user_id
) page_counts ON page_counts.user_id = users.user_id

+---------+------------+------------+
| user_id | post_count | page_count |
+---------+------------+------------+
|       1 |          3 |          0 |
|       2 |          2 |          2 |
|       3 |          0 |          5 |
+---------+------------+------------+