SELECT cr1.entity_id, cr1.user_id, cr1.value
FROM core_rating cr1
where cr1.timestamp=(select max(cr2.timestamp) from core_rating cr2 where cr1.user_id = cr2.user_id)
GROUP BY cr1.entity_id, cr1.user_id, DATE_FORMAT(cr1.timestamp, '%Y-%m-%d %h:%i:00')
order by cr1.timestamp