Question

我在wp_post和wp_post_meta WP数据库中有数据：一个包含“工作坊”的唯一条目，第二个包含与每个研讨会相关的元数据。表格如下：

WP_POST TABLE

| post ID   | post title    | post type | post content etc.
|---------------------------------------------------------
|   1       | workshop 1    | workshop  | cooking with apples
|   2       | workshop 2    | workshop  | cooking with pears
|   3       | workshop 3    | workshop  | cooking with bananas

WP META TABLE

| post ID   | meta key      | meta value    | etc.
|---------------------------------------------------------
|    1      | summary       | apples        | ..
|    1      | date          | 20100518      | ..
|    1      | duration      | 1 hour        | ..
|    2      | summary       | pears         | ..
|    2      | date          | 20100623      | ..
|    2      | duration      | 1/2 day       | ..
|    3      | summary       | bananas       | ..
|    3      | date          | 20101111      | ..
|    3      | duration      | all day       | ..

我一直在玩查询。

SELECT post_title, post_date, post_type, meta_key, meta_value, post_content
FROM wp_posts as post INNER JOIN wp_postmeta as meta ON post.ID = meta.post_id 
WHERE post.post_status = "publish" AND post.post_type = "workshop"

此查询给了我一张看起来像这样的表。

| post ID   | post title    | post type     | meta key      | meta value    | etc.
|--------------------------------------------------------------------------------
|    1      | workshop 1    | workshop      | summary       | apples        | ..
|    1      | workshop 1    | workshop      | date          | 20100518      | ..
|    1      | workshop 1    | workshop      | duration      | 1 hour        | ..
|    2      | workshop 2    | workshop      | summary       | pears         | ..
|    2      | workshop 2    | workshop      | date          | 20100623      | ..
|    2      | workshop 2    | workshop      | duration      | 1/2 day       | ..
|    3      | workshop 3    | workshop      | summary       | bananas       | ..
|    3      | workshop 3    | workshop      | date          | 20101111      | ..
|    3      | workshop 3    | workshop      | duration      | all day       | ..

我需要做的是对元键值“ date”进行排序，但是我不确定执行此操作的最佳方法。我可以按“元键”日期的“元值”排序吗？

我思考我需要创建一个这样的表才能实现，但是不知道该怎么做，即使这是必需的方法。

| post ID   | post title    | summary   | date      | duration | etc.
|--------------------------------------------------------------
|   1       | workshop 1    | apples    | 20100518  | 1 hour
|   2       | workshop 2    | pears     | 20100623  | 1/2 day
|   3       | workshop 3    | bananas   | 20101111  | all day

Answer 1

您可以仅使用join对日期进行排序：

select p.*, d.meta_value as date
from wp_post p join
     wp_meta d
     on d.post_id = p.post_id and d.meta_key = 'date'
order by d.meta_value;

Answer 2

您可以使用汇总功能在每个帖子的不同列中显示元数据信息，例如

SELECT p.post_title, 
  p.post_date,
  p.post_type,
  p.post_content,
  MAX(CASE WHEN m.meta_key = 'summary' THEN m.meta_value ELSE NULL END) summary,
  MAX(CASE WHEN m.meta_key = 'duration' THEN m.meta_value ELSE NULL END) duration,
  MAX(CASE WHEN m.meta_key = 'date' THEN m.meta_value ELSE NULL END) `date`
FROM wp_posts as p
INNER JOIN wp_postmeta as m ON p.ID = m.post_id 
WHERE p.post_type = "workshop" AND p.post_status = "publish"
GROUP BY p.post_title, 
  p.post_date,
  p.post_type,
  p.post_content
ORDER BY STR_TO_DATE(MAX(CASE WHEN m.meta_key = 'date' THEN m.meta_value ELSE NULL END), '%Y%m%d')

要使用元数据值对数据集进行排序，您首先需要使用STR_TO_DATE

将其转换为日期对象

Demo

查询两个表并根据值创建列以启用排序

2 个答案: