MySql 查询没有返回正确的数据

Question

我有一个 Wordpress MySQL 数据库，我需要创建一个自定义查询以使用 SQL。我正在尝试返回“date_start”值小于当天且“date_end”值大于或等于当天的当前事件（帖子）。我知道应该返回一条数据记录，但当我尝试同时搜索“date_start”和“date_end”时没有返回任何内容

这是我的旧 SQL 语句：

select ID, post_name, meta_id, meta_key, meta_value from wp_posts inner join wp_postmeta on wp_posts.ID = wp_postmeta.post_id and ((meta_key='date_end' and meta_value >= CURDATE() + interval 1 day) and (meta_key='date_start' and meta_value < CURDATE())) where post_type='programs' order by meta_value

新的 SQL 语句：

    SELECT
    ID,
    post_name,
    (SELECT meta_value FROM wp_postmeta WHERE wp_postmeta.post_id = ID AND meta_key = 'date_start') AS 'date_start',
    (SELECT meta_value FROM wp_postmeta WHERE wp_postmeta.post_id = ID AND meta_key = 'date_end') AS 'date_end'
FROM wp_posts
WHERE
    post_type = 'programs'
    AND ((CURDATE() >= (SELECT meta_value FROM wp_postmeta WHERE wp_postmeta.post_id = ID AND meta_key = 'date_start'))
    AND (CURDATE() <= (SELECT meta_value FROM wp_postmeta WHERE wp_postmeta.post_id = ID AND meta_key = 'date_end')))
ORDER BY `wp_posts`.`ID` ASC

返回的日期是：

ID      post_name                   date_start  date_end
1221    culture-analytics           20160307    20160610
2446    culture-analytics-tutorials 20160308    20160311

我还尝试过内部连接的 date_start 和 date_end 部分在 WHERE 子句中的位置。

重要提示：wp_postmeta 是多对​​一模式，而 'date_start' 和 'date_end' 是单独的记录，但都指向同一个 PostID

似乎是什么问题。

Answer 1

您对 meta_key 有两个相互冲突的约束。您的查询要求 meta_key 同时等于“date_start”和“date_end”。

不妨试试这样的：

SELECT
    ID,
    post_name,
    meta_id,
    (SELECT meta_value FROM wp_postmeta WHERE wp_postmeta.post_id = ID AND meta_key = 'date_start') AS 'date_start',
    (SELECT meta_value FROM wp_postmeta WHERE wp_postmeta.post_id = ID AND meta_key = 'date_end') AS 'date_end'
FROM wp_posts
WHERE
    post_type = 'programs'
    AND (SELECT meta_value FROM wp_postmeta WHERE wp_postmeta.post_id = ID AND meta_key = 'date_start') < CURDATE()
    AND (SELECT meta_value FROM wp_postmeta WHERE wp_postmeta.post_id = ID AND meta_key = 'date_end') >= (CURDATE() + INTERVAL 1 DAY)
ORDER BY 4

我无权访问 Wordpress 数据库，所以我没有运行它，但它可能会工作...

Answer 2

@obe 在他的回答中发现了您原始查询的核心问题；但我会通过额外的连接而不是四个子查询来解决它：

SELECT ID, post_name, meta_id
   , beginMeta.meta_key As beginKey, endMeta.meta_key AS endKey
   , beginMeta.meta_value AS beginDate
   , endMeta.meta_value AS endDate
FROM wp_posts 
INNER JOIN wp_postmeta AS endMeta 
   ON wp_posts.ID = endMeta.post_id 
   AND endMeta.meta_key='date_end' 
   AND endMeta.meta_value >= CURDATE() + interval 1 day 
INNER JOIN wp_postmeta AS beginMeta 
   ON wp_posts.ID = beginMeta .post_id 
   AND beginMeta.meta_key='date_start' 
   AND beginMeta.meta_value < CURDATE() 
WHERE post_type='programs' 
ORDER BY beginDate, endDate
;

编辑：假设 (post_id, meta_key) 组合在 wp_postmeta 中是唯一的。