如果我刪除USING (nid,sid)
,我得到的列是ambigious錯誤。我不太明白USING
在這裏做什麼?它是否加入了nid和sid從子查詢返回到nid,sid在外部select查詢中?不明白在MySQL中使用語法
SELECT sid, nid, max_rating FROM outcomes
JOIN (SELECT nid, sid, MAX(rating) AS max_rating from outcomes group by nid, sid) AS newtable
USING (nid, sid)
WHERE rating = max_rating AND name LIKE '%test%'
請注意,這僅在PostgreSQL和MySQL中受支持。 – Subodh 2012-02-29 12:32:29