我当前返回的行不止一个，因此我尝试使用此联接来联接最新的项目。
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) )
但出现错误“ SQL错误：表'web13-a-tablename.wp_posts1'不存在”。
我下面的原始代码返回了太多结果。
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。我只想获得一行，并且想选择最大的f_ID。 http://sqlfiddle.com/#!2/97ee9/3/0
所需结果：
ID POST_TITLE F_IMAGE F_ID
--------------------------------------------
2365 John Jones IMG_URL 2490
2385 Becky Smith IMG_URL 2390
最佳答案
将子查询更改为：
SELECT MAX(post_parent) FROM wp_posts as w3 WHERE w3.post_parent = wp_posts.ID
UPDATE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
关于mysql - MYSQL-帮助仅加入1行，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/16787879/