Wordpress SQL：获取帖子类别和标签

Question

我想查询存储在 MySQL 数据库中的 Wordpress 数据，以获得带有列的结果：

1. post_id
2. 类别
3. 逗号分隔的标签

预期输出：

+---------------+----------+----------------+
| post_id       | category | tags           |
|---------------+----------+----------------+
| 213           | news     | tag1,tag2,tag3 |
+---------------+----------+----------------+

这是我尝试过的：

SELECT
    p.id,
    c.name,
    GROUP_CONCAT(t.`name`)
FROM wp_posts p
JOIN wp_term_relationships cr 
    on (p.`id`=cr.`object_id`)
JOIN wp_term_taxonomy ct 
    on (ct.`term_taxonomy_id`=cr.`term_taxonomy_id` and ct.`taxonomy`='category')
JOIN wp_terms c 
    on (ct.`term_id`=c.`term_id`)
JOIN wp_term_relationships tr 
    on (p.`id`=tr.`object_id`)
JOIN wp_term_taxonomy tt 
    on (tt.`term_taxonomy_id`=tr.`term_taxonomy_id` 
   and tt.`taxonomy`='post_tag')
JOIN wp_terms t 
    on (tt.`term_id`=t.`term_id`)

结果，我得到了我想要的列，以及预期的内容，但我只得到了一行。

我究竟做错了什么？

Answer 1

正如评论中所指出的，我包含了一个聚合函数，但没有“group by”子句。

现在这似乎有效（刚刚添加了该GROUP BY行）：

SELECT
    p.id,
    p.post_name,
    c.name,
    GROUP_CONCAT(t.`name`)
FROM wp_posts p
JOIN wp_term_relationships cr
    on (p.`id`=cr.`object_id`)
JOIN wp_term_taxonomy ct
    on (ct.`term_taxonomy_id`=cr.`term_taxonomy_id`
    and ct.`taxonomy`='category')
JOIN wp_terms c on
    (ct.`term_id`=c.`term_id`)
JOIN wp_term_relationships tr
    on (p.`id`=tr.`object_id`)
JOIN wp_term_taxonomy tt
    on (tt.`term_taxonomy_id`=tr.`term_taxonomy_id`
    and tt.`taxonomy`='post_tag')
JOIN wp_terms t
    on (tt.`term_id`=t.`term_id`)
GROUP BY p.id


+---------------+----------+----------------+
| post_id       | category | tags           |
|---------------+----------+----------------+
| 213           | news     | tag1,tag2,tag3 |
+---------------+----------+----------------+
| 216           | whatever | tag2,tag3      |
+---------------+----------+----------------+

谢谢草莓！