尋找作者的最新職位

Question

我在爲我的WordPress博客建立一個「作者」頁面，列出所有當前網站貢獻者以及各種其他信息，例如發佈的帖子數量，最後發表的日期等

谷歌和Wordpress Codex指出我在MySQL中使用子查詢來在一個查詢中提取我需要的所有數據，並且它對於獲取每個作者發佈的帖子數量非常有用。

我無法工作的是找到每個作者的最新帖子的帖子ID。

說，工程沒有最新的帖子目前查詢：

SELECT users.ID, (SELECT count(*) FROM posts, users WHERE users.ID = posts.post_author AND posts.post_type = 'post' AND posts.post_status = 'publish') AS post_count FROM users ORDER BY post_count DESC 

我試圖得到最新帖子ID爲每個作者（ 'latest_post_ID'）：

SELECT users.ID, (SELECT count(*) FROM posts, users WHERE users.ID = posts.post_author AND posts.post_type = 'post' AND posts.post_status = 'publish') AS post_count, (SELECT posts.ID FROM posts, users WHERE users.ID = posts.post_author AND posts.post_type = 'post' AND posts.post_status = 'publish' ORDER BY posts.post_date DESC LIMIT 1) AS latest_post_ID FROM users ORDER BY post_count DESC 

的問題是與加子查詢 - 查詢將查找任何與任何作者匹配發布的帖子，而不是我想要的（'users.ID = posts.post_author'）。

我非常感謝它，如果有人用一些SQL-fu可以指出我濫用和/或濫用MySQL子查詢的地方。

Answer 1

試試這個。

SELECT a.ID, 

(SELECT count(*) 
FROM posts 
WHERE a.ID = posts.post_author 
AND posts.post_type = 'post' 
AND posts.post_status = 'publish') AS post_count, 

(SELECT posts.ID 
FROM posts 
WHERE a.ID = posts.post_author 
AND posts.post_type = 'post' 
AND posts.post_status = 'publish' 
ORDER BY posts.post_date DESC LIMIT 1) AS latest_post_ID 

FROM users As a 
ORDER BY post_count DESC 

Answer 2

下面的查詢應該在MySQL的工作：

SELECT posts.ID FROM posts, 
(SELECT MAX(posts.post_date) AS max_date, 
posts.post_author AS author 

FROM posts 

WHERE users.ID = posts.post_author 

GROUP BY posts.post_author) AS max_date_table 

WHERE posts.post_date = max_date_table.max_date AND 
posts.post_author = max_date_table.author 

Answer 3

SELECT u.id, 
     COUNT(*) AS post_count, 
     MAX(p.id) AS latest_post_id 
    FROM POSTS p 
    JOIN USERS u ON u.ID = p.post_author 
    WHERE p.post_type = 'post' 
    AND p.post_status = 'publish' 
GROUP BY u.id 
ORDER BY post_count DESC 

我不建議在SELECT子句中使用SELECTS的。雖然他們工作，他們將提供最差的表現。