LEFT JOIN不起作用

Question

我有2个分类： city和street 。

我需要为我的一个插件获取postmeta 。

仅针对一种分类法的工作代码：

SELECT *
FROM $wpdb->postmeta
LEFT JOIN $wpdb->posts ON($wpdb->posts.ID = $wpdb->postmeta.post_id)
LEFT JOIN $wpdb->term_relationships ON ($wpdb->postmeta.post_id = $wpdb->term_relationships.object_id)
LEFT JOIN $wpdb->term_taxonomy ON ($wpdb->term_relationships.term_taxonomy_id = $wpdb->term_taxonomy.term_taxonomy_id)
WHERE meta_key LIKE 'rwp_rating%'
  AND ($wpdb->term_taxonomy.taxonomy = 'city'
       AND $wpdb->term_taxonomy.term_id = '2')

但如果我追加

AND ($wpdb->term_taxonomy.taxonomy = 'street' AND $wpdb->term_taxonomy.term_id = '5')

它返回空结果。

我还试着这样做：

SELECT *
FROM $wpdb->postmeta
LEFT JOIN $wpdb->posts ON ($wpdb->posts.ID = $wpdb->postmeta.post_id)
LEFT JOIN $wpdb->term_relationships ON ($wpdb->postmeta.post_id = $wpdb->term_relationships.object_id)
LEFT JOIN $wpdb->term_taxonomy AS t1 ON ($wpdb->term_relationships.term_taxonomy_id = t1.term_taxonomy_id)
LEFT JOIN $wpdb->term_taxonomy AS t2 ON ($wpdb->term_relationships.term_taxonomy_id = t2.term_taxonomy_id)
WHERE meta_key LIKE 'rwp_rating%'
  AND (t1.taxonomy = 'city'
       AND t1.term_id = '2')
  AND (t2.taxonomy = 'street'
       AND t2.term_id = '3331');

而且它也不起作用。

请注意：我需要匹配两者，例如： city = 2 AND street = 2
not： city = 2 OR street = 2

Answer 1

您的第一次尝试将无法工作，因为单个分类记录不能包含街道和城市。

更新您的第二次尝试：

SELECT * FROM $wpdb->postmeta 
LEFT JOIN $wpdb->posts ON ($wpdb->posts.ID = $wpdb->postmeta.post_id) 
LEFT JOIN $wpdb->term_relationships ON ($wpdb->postmeta.post_id = $wpdb->term_relationships.object_id) 
LEFT JOIN $wpdb->term_taxonomy as t1 ON ($wpdb->term_relationships.term_taxonomy_id = t1.term_taxonomy_id AND t1.taxonomy = 'city') 
LEFT JOIN $wpdb->term_taxonomy as t2 ON ($wpdb->term_relationships.term_taxonomy_id = t2.term_taxonomy_id AND t2.taxonomy = 'street') 
WHERE meta_key LIKE 'rwp_rating%' AND t1.term_id = '2' AND t2.term_id = '3331');