寻找作者的最新职位

Question

我在为我的WordPress博客建立一个“作者”页面，列出所有当前网站贡献者以及各种其他信息，例如发布的帖子数量，最后发表的日期等

谷歌和Wordpress Codex指出我在MySQL中使用子查询来在一个查询中提取我需要的所有数据，并且它对于获取每个作者发布的帖子数量非常有用。

我无法工作的是找到每个作者的最新帖子的帖子ID。

说，工程没有最新的帖子目前查询：

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 

我试图得到最新帖子ID为每个作者（ '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 

的问题是与加子查询 - 查询将查找任何与任何作者匹配发布的帖子，而不是我想要的（'users.ID = posts.post_author'）。

我非常感谢它，如果有人用一些SQL-fu可以指出我滥用和/或滥用MySQL子查询的地方。

Answer 1

试试这个。

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

下面的查询应该在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 

我不建议在SELECT子句中使用SELECTS的。虽然他们工作，他们将提供最差的表现。