zsák

SELECT diak FROM diakok WHERE id IN(SELECT diakok_id FROM(SELECT MAX(avg_salary), diakok_id FROM (SELECT AVG(erdemjegy) AS avg_salary, diakok_id FROM erdemjegyek AS e WHERE e.diakok_id IN(SELECT d.diakok_id FROM diak_osztaly AS d WHERE d.osztalyok_id = 7) GROUP BY e.diakok_id) AS f) AS d)