Question

我正在为wordpress中的帖子使用过滤器，它使用来自postsmeta的数据：我的日期过滤器正在运行并向我提供此查询：

工作查询结果：

SELECT SQL_CALC_FOUND_ROWS wp_posts.ID 
FROM wp_posts 
LEFT JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id) 
WHERE 1=1 AND YEAR(wp_posts.post_date)=2017 
AND MONTH(wp_posts.post_date)=03 AND wp_posts.post_type = 'projects' 
AND (wp_posts.post_status = 'publish' OR wp_posts.post_status = 'future' 
OR wp_posts.post_status = 'draft' OR wp_posts.post_status = 'pending' 
OR wp_posts.post_status = 'private') 
GROUP BY wp_posts.ID 
ORDER BY wp_posts.post_date DESC LIMIT 0, 20

当我通过postmeta.meta_value过滤时，我得到一个额外的INNER JOIN 导致问题：

过滤（不完全正常）：

$query->set('meta_query', array(
   array(
      'key' => 'project_cust_id',
      'value' => $project_cust_id,
      'compare' => '=' 
   )
));

查询（非工作结果）：

SELECT SQL_CALC_FOUND_ROWS wp_posts.ID 
FROM wp_posts 
INNER JOIN wp_postmeta ON ( wp_posts.ID = wp_postmeta.post_id ) 
LEFT JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id) 
WHERE 1=1 AND ( ( wp_postmeta.meta_key = 'project_cust_id' 
AND wp_postmeta.meta_value = '12345' ) ) AND wp_posts.post_type = 'projects' 
AND (wp_posts.post_status = 'publish' OR wp_posts.post_status = 'future' 
OR wp_posts.post_status = 'draft' OR wp_posts.post_status = 'pending' 
OR wp_posts.post_status = 'private') 
GROUP BY wp_posts.ID 
ORDER BY wp_posts.post_date DESC LIMIT 0, 20

当我直接查询到我的数据库时，我在下面没有得到任何结果和错误，但当我删除额外的行：INNER JOIN wp_postmeta ON ( wp_posts.ID = wp_postmeta.post_id )或当我删除行时：LEFT JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id)我得到的结果为预期

编辑：MySQL返回错误：不是唯一值表/别名：＆＃39; wp_postmeta＆＃39;

我的问题是：

为什么我的代码会添加另一个INNER JOIN？
如何删除/阻止此额外的INNER JOIN或LEFT JOIN？

任何帮助都将不胜感激。

Answer 1

由于您要在where子句中的wp_postmeta表中过滤值，LEFT JOIN将像INNER JOIN一样，因为它只会返回wp_postmeta中具有匹配条件的值表。因此，拥有LEFT JOIN或INNER JOIN或两者都不应有所作为。如果您希望联接的行为类似LEFT JOIN，则应将wp_postmeta表的任何条件添加到JOIN而不是WHERE子句。

SELECT SQL_CALC_FOUND_ROWS wp_posts.ID 

FROM   wp_posts 

       LEFT JOIN wp_postmeta 
       ON wp_posts.ID = wp_postmeta.post_id
       AND wp_postmeta.meta_key = 'project_cust_id' 
       AND wp_postmeta.meta_value = '12345'

WHERE  1=1 AND wp_posts.post_type = 'projects' 
       AND (wp_posts.post_status = 'publish' OR wp_posts.post_status = 'future' 
       OR wp_posts.post_status = 'draft' OR wp_posts.post_status = 'pending' 
       OR wp_posts.post_status = 'private') 

GROUP BY wp_posts.ID 

ORDER BY wp_posts.post_date DESC LIMIT 0, 20

Answer 2

感谢大家的输入，但事实证明我的编码没有任何问题，显然有一些其他插件在我发出过滤器参数时发出GET参数，当设置此参数时返回FALSE，我通过在该插件中添加！EMPTY来修复它，之后它就像一个魅力。

Wordpress查询添加INNER / LEFT JOIN。为什么或如何删除/阻止INNER / LEFT JOIN？

2 个答案: