MySQL：按語句分組前的結果排序

Question

基本上，我有一個銅礦畫廊，我想在主頁上顯示最近4個更新的相冊。以下是我迄今爲止的查詢。它基本上得到最新的照片。子查詢可以自行完成，但是當它將它們分組以獲取每個專輯時，它似乎沒有從列表中獲取最新的專輯。

SELECT * 
FROM (
SELECT c.cid, c.name AS catname, a.aid, a.title AS albumtitle, a.category, p.aid AS albumid,p.filepath,p.filename,p.ctime AS creationtime,p.title AS pictitle,p.approved 
FROM cpg145_pictures AS p LEFT JOIN `cpg145_albums` AS a ON p.aid = a.aid LEFT JOIN `cpg145_categories` AS c ON a.category = c.cid 
WHERE p.approved='YES' AND a.category IN (47,48) 
ORDER BY p.ctime DESC) AS T 
GROUP BY albumid 
ORDER BY creationtime DESC 
LIMIT 4 

Answer 1

我想出了答案。顯然，在MariaDB中你必須給子查詢一個限制，以便正確排序。所以：

SELECT * 
FROM (
SELECT c.cid, c.name AS catname, a.aid, a.title AS albumtitle, a.category, p.aid AS albumid,p.filepath,p.filename,p.ctime AS creationtime,p.title AS pictitle,p.approved 
FROM cpg145_pictures AS p LEFT JOIN `cpg145_albums` AS a ON p.aid = a.aid LEFT JOIN `cpg145_categories` AS c ON a.category = c.cid 
WHERE p.approved='YES' AND a.category IN (47,48) 
ORDER BY p.ctime DESC 
LIMIT 200) AS T 
GROUP BY albumid 
ORDER BY creationtime DESC 
LIMIT 4