SELECT item_name AS 'アイテム名' ,
(SUM(cost) / SUM(count)) AS '平均価格',
SUM(count) AS '件数'
FROM item_detail_tbl
WHERE item_name LIKE 'ディーヴァ%' AND
datetime > (NOW() - INTERVAL 1 DAY) AND
world LIKE 'Breidablik' AND
smelting LIKE 0
GROUP BY item_name
ORDER BY `件数` DESC;