Try this:
SELECT u.username, ucf.user_id,
ucf.value,
ucf.updated_at AS reltime$time
FROM user_custom_fields ucf, users u
WHERE ucf.name = 'user_field_9'
and ucf.user_id=u.id
AND LENGTH(ucf.value) > 1
ORDER BY ucf.updated_at DESC
Try this:
SELECT u.username, ucf.user_id,
ucf.value,
ucf.updated_at AS reltime$time
FROM user_custom_fields ucf, users u
WHERE ucf.name = 'user_field_9'
and ucf.user_id=u.id
AND LENGTH(ucf.value) > 1
ORDER BY ucf.updated_at DESC