SELECT
persons.*,cities.name AS city,
countries.NAME AS country, DATE_FORMAT(FROM_DAYS(TO_DAYS(NOW())-TO_DAYS(persons.birthday)), '%Y')+0 AS age,
ROUND(ratings.rating/2) as rating
FROM persons
LEFT JOIN ratings ON ratings.person_id = persons.id
INNER JOIN cities ON cities.id = persons.id
INNER JOIN countries ON cities.country_id = countries.id
GROUP BY persons.id