https://rodb.aws.0nyx.net/ropma/index.php?route=/table/sql&db=pigeon&table=item_detail_tbl
に↓の内容を入れて実行
SELECT idential.item_name AS 'アイテム名',
SUM(sales.cost) / SUM(sales.count) AS '平均価格',
SUM(sales.count) AS '件数'
FROM item_name_tbl idential
LEFT JOIN item_detail_tbl sales ON (idential.item_name = sales.item_name)
WHERE idential.item_name LIKE '%のカード%' AND
idential.description LIKE '%[アルカナ]と%全てのスロットに%' AND
sales.datetime >= (NOW() - INTERVAL 3 MONTH)
GROUP BY idential.item_name
ORDER BY 2 DESC,1