I couldn’t find an existing one, but maybe something like this:
SELECT u.id AS user_id,
u.created_at,
u.approved_at,
us.days_visited
FROM users u
JOIN user_stats us ON u.id = us.user_id
WHERE u.approved_at IS NOT NULL
ORDER BY u.created_at DESC
Or one with a little extra to make it more readable:
SELECT u.id AS user_id,
CONCAT(u.created_at::date, ' at ', to_char(u.created_at, 'HH:MM')) "user_created",
CONCAT(u.approved_at::date, ' at ', to_char(u.approved_at, 'HH:MM')) "user_approved",
us.days_visited
FROM users u
JOIN user_stats us ON u.id = us.user_id
WHERE u.approved_at IS NOT NULL
ORDER BY u.created_at DESC