MySQL组以显示最新结果
-
10-10-2019 - |
题
我正在尝试查询mysql订购然后组...这是一个问题,在这里出现了很多问题,我发现一个似乎与我相关的答案: 通过查询获得一个mySQL组,以最高值显示该组
但是,我发现在进行分组之前,它仍然没有订购。
具体而言,我要做的是使用WordPress自定义帖子类型通过称为“ Date”的元数据字段进行分组,该字段按帖子日期订购。
这是我的查询:
SELECT
`ID`, `date`, `post_date`, `date_rank`
FROM (
SELECT
`Post`.`ID`,
`Post`.`post_date`,
`PostData`.`meta_value` AS `date`,
CASE
WHEN @data_date = `PostData`.`meta_value` THEN @rowum := @rownum + 1
ELSE @rownum := 1
END AS date_rank,
@data_date := `PostData`.`meta_value`
FROM
`".$this->wpdb->posts."` AS `Post`
JOIN
`".$this->wpdb->postmeta."` AS `PostData`
ON `Post`.`ID` = `PostData`.`post_id` AND `PostData`.`meta_key` = 'date'
JOIN (SELECT @rownum := 0, @data_date := '') AS `vars`
WHERE
`Post`.`post_type` = 'my_post_type'
AND
`Post`.`post_status` = 'publish'
ORDER BY `Post`.`post_date` DESC
) AS `x`
WHERE date_rank = 1
ORDER BY `date` ASC
所需的结果是每个“日期”的帖子(这是一个元字段),根据post_date,该“日期”的最新帖子。
解决方案
SELECT *
FROM (
SELECT DISTINCT meta_value
FROM postdata pd
WHERE pd.meta_key = 'date'
) pd
JOIN post p
ON p.id =
(
SELECT post_id
FROM postdata pdi
JOIN post pi
ON pi.id = pdi.post_id
WHERE pdi.meta_key = 'date'
AND pdi.meta_value = pd.meta_value
ORDER BY
pi.post_date DESC, pi.id DESC
LIMIT 1
)
不隶属于 StackOverflow