php - Wordpress 分类查询中的 double

Question

我从这个 wordpress 查询中得到了 double :

SELECT LEFT(main.post_title , 1) AS `character`,
            main.post_title AS title,
            main.post_content AS content,
            parent_data.name AS parent_title,
            root_data.name AS root_title,
            thumbnail_data.meta_value AS thumbnail_url,
            main.ID
        FROM wp_jlwx_posts AS main
            INNER JOIN wp_jlwx_term_relationships AS parent ON main.ID = parent.object_id
            INNER JOIN wp_jlwx_term_taxonomy AS parent_taxonomy ON parent.term_taxonomy_id = parent_taxonomy.term_taxonomy_id
            INNER JOIN wp_jlwx_terms AS parent_data ON parent_taxonomy.term_id = parent_data.term_id
            INNER JOIN wp_jlwx_term_taxonomy AS root_taxonomy ON parent_taxonomy.parent = root_taxonomy.term_taxonomy_id
            INNER JOIN wp_jlwx_terms AS root_data ON root_taxonomy.term_taxonomy_id = root_data.term_id
            LEFT JOIN wp_jlwx_postmeta AS linker    ON main.ID = linker.post_id AND linker.meta_key = '_thumbnail_id'
            LEFT JOIN wp_jlwx_postmeta AS thumbnail_data    ON linker.meta_value = thumbnail_data.post_id
            WHERE main.post_type = 'business' 
                AND main.post_status = 'publish'
                $search_where_clause
            $character_have_clause
            ORDER BY root_title, parent_title, title

让我惊讶的第一件事是我在分类表上加入了两次。如何确保“主”表中的每一行只返回一行？

(编辑)我已经能够将范围缩小到缩略图连接，我在其中从元表接收额外的数据:例如a:5:{s:5:"宽度";i:960;s:6:"高度"...

Answer 1

我已经找到了问题:

Wordpress 在将缩略图添加到元表中时会存储元数据。

该位置使用meta_key:_wp_attached_file存储，而额外数据则使用meta_key:_wp_attachment_metadata存储。

因此，如果我将 meta_key = "_wp_attached_file"添加到最后一个连接，我的问题就解决了。