Question

我目前正在返回多行，所以我尝试使用此连接加入最近的项目。

LEFT OUTER JOIN wp_posts wp_posts1 ON (wp_posts.ID = (SELECT MAX(post_parent) FROM wp_posts1 WHERE wp_posts1.post_parent = wp_posts.ID) )

但我收到错误'SQL Error：Table'web13-a-tablename.wp_posts1'不存在'。

下面的原始代码会返回太多结果。

SELECT 
wp_posts.ID, 
wp_posts.post_title, 
wp_posts1.guid AS f_image,
wp_posts1.id AS f_ID 
FROM wp_posts 
LEFT OUTER JOIN wp_posts wp_posts1 ON (wp_posts.ID = wp_posts1.post_parent) AND wp_posts1.post_type = 'attachment'  
WHERE wp_posts.post_type = 'custom' 
AND wp_posts.post_status = 'publish' 
AND (wp_posts.post_title LIKE '%smith%' OR wp_posts.post_title LIKE '%jones%')
ORDER BY 
f_ID DESC

SQLFiddle显示选中的多行。我想得到一行，我想选择最大的f_ID。 http://sqlfiddle.com/#!2/97ee9/3/0

需要的结果：

ID       POST_TITLE       F_IMAGE       F_ID
--------------------------------------------
2365     John Jones       IMG_URL       2490
2385     Becky Smith      IMG_URL       2390

Answer 1

将子查询更改为：

SELECT MAX(post_parent) FROM wp_posts as w3 WHERE w3.post_parent = wp_posts.ID

更新将fiddle中的查询更改为：

SELECT 
  wp_posts.ID, 
  wp_posts.post_title, 
  wp_posts1.guid AS f_image,
  MAX(wp_posts1.id) AS f_ID 
FROM wp_posts 
LEFT OUTER JOIN wp_posts wp_posts1 ON (wp_posts.ID = wp_posts1.post_parent) AND wp_posts1.post_type = 'attachment'  
WHERE wp_posts.post_type = 'custom' 
  AND wp_posts.post_status = 'publish' 
  AND (wp_posts.post_title LIKE '%smith%')
GROUP BY
  wp_posts.ID

MYSQL - 帮助加入一行

1 个答案: