Done 
and I can download via CSV
SELECT u.username
FROM badge_posts p
JOIN topics t ON p.topic_id = t.id
JOIN users u ON p.user_id = u.id
WHERE t.id = '1010'
GROUP BY p.user_id,u.username
Done and I can download via CSV
SELECT u.username
FROM badge_posts p
JOIN topics t ON p.topic_id = t.id
JOIN users u ON p.user_id = u.id
WHERE t.id = '1010'
GROUP BY p.user_id,u.username