Sql 查询Wordpress缩略图

我正在努力获取wordpress博客中帖子的缩略元数据，以及它们的类别和一些其他数据。 缩略图数据已序列化，稍后我将取消序列化

以下是我的疑问：

    SELECT wpostmeta.meta_value AS url,
    wposts.post_content, wposts.post_title, wposts.post_status, wposts.post_name,
    cat_terms.name AS category_name, cat_terms.term_id AS category_id,
    ttable.meta_value AS thumb_data
    FROM `wp_postmeta` AS wpostmeta,
    `wp_posts` AS wposts
    INNER JOIN wp_term_relationships AS cat_term_relationships ON (wposts.ID = cat_term_relationships.object_id)
    INNER JOIN wp_term_taxonomy AS cat_term_taxonomy ON (cat_term_relationships.term_taxonomy_id = cat_term_taxonomy.term_taxonomy_id AND cat_term_taxonomy.taxonomy = 'category')
    INNER JOIN wp_terms AS cat_terms ON (cat_term_taxonomy.term_id = cat_terms.term_id)
    LEFT JOIN `wp_postmeta` AS ttable ON (wposts.ID = ttable.post_id AND ttable.meta_key = '_wp_attachment_metadata')
    WHERE wposts.ID = wpostmeta.post_id AND wpostmeta.meta_key = 'url'
    AND wposts.post_type = 'post'

除附件部分外，一切正常。”“thumb_数据”为空

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你能帮我解决这个问题吗？

你能准确地解释一下你想要实现的目标吗？在很多情况下，没有必要直接访问数据库

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例如，您可以使用带有“post\u type”=>“attachment”和“post\u mime\u type”=>“image”的get\u posts来获取图像附件，然后输出元数据，并且内置了许多函数来处理缩略图的大小调整、显示和裁剪，例如get\u post\u thumbnail（）等。

此查询解决了我的问题：

$sql = "SELECT wposts.ID AS ID, thumbposts.ID AS thumbposts_ID,
        postmeta.meta_value AS url,
        wposts.post_content, wposts.post_title, wposts.post_status, wposts.post_name,
        cat_terms.name AS category_name, cat_terms.term_id AS category_id,
        thumb.meta_value AS thumb_data

        FROM `wp_postmeta` AS postmeta,
        `wp_posts` AS thumbposts,
        `wp_postmeta` AS thumb,
        `wp_posts` AS wposts

        INNER JOIN wp_term_relationships AS cat_term_relationships ON (wposts.ID = cat_term_relationships.object_id)
        INNER JOIN wp_term_taxonomy AS cat_term_taxonomy ON (cat_term_relationships.term_taxonomy_id = cat_term_taxonomy.term_taxonomy_id AND cat_term_taxonomy.taxonomy = 'category')
        INNER JOIN wp_terms AS cat_terms ON (cat_term_taxonomy.term_id = cat_terms.term_id)

        WHERE wposts.ID = postmeta.post_id
        AND postmeta.meta_key = 'url'

        AND thumbposts.post_parent = wposts.ID
        AND thumbposts.post_type = 'attachment'

        AND thumb.post_id = thumbposts.ID
        AND thumb.meta_key = '_wp_attachment_metadata'

        AND wposts.post_type = 'post'";

    if($filter == 1){
        $sql .= " AND cat_terms.term_id = '1'";
    }
    if($filter == 2){
        $sql .= " AND cat_terms.term_id = '3'";
    }

    $sql .= " GROUP BY wposts.ID
        ORDER BY wposts.post_date ASC";