SELECT
sync.id_allievo AS id_allievo,
COUNT(sync.id_allievo) AS Schede,
LI.Domande AS Domande,
IFNULL(LI.errori, 0) MediaErrori
FROM sync
LEFT JOIN allievo A ON A.id_allievo = sync.id_allievo
LEFT JOIN clientescuola CS ON CS.id_clienteScuola = A.id_clienteScuola
LEFT join listato LI ON LI.tipo = A.listatoQuiz
JOIN
(SELECT AVG(Media) as MediaErrori FROM (SELECT errori as Media FROM sync WHERE id_allievo= ". $id_allievo . " AND tipo = 'TipoEsame' ORDER BY `sync`.`dataFine` DESC Limit 15 )as MediaErrori
) MediaErrori
WHERE ((sync._Stato <> "D") AND (sync._Stato <> "X") AND (sync.tipo = "TipoEsame"))
AND CS.id_sedeClienteNeca = 5111
AND sync.id_allievo = 345266
GROUP BY sync.id_allievo