Php mysql按日期时间顺序描述

员额表

ID           post_date 
1      2013-10-20:01:00:00
6      2013-09-20:01:00:00

术语关系图

object_id    term_taxonomy_id    term_order

1               1                    0
1               2                    0
1               3                    0
6               1                    0
6               1                    0

术语分类图

term_taxonomy_id     term_id    taxonomy    parent
1                     1         category      0
2                     2         post_tag      0
3                     3         post_tag      0
4                     4         category      1

--

tax.parent=顶级类别id 发布日期类型数据类型

---

ORDER BY datetime DESC=排序不正确：（

尝试使用表别名：：

或p.post_date DESC的订单

如果您的代码有问题，请发布结果顺序以及您期望的顺序。我也不知道最后两行应该说什么。结果截止日期：11.10.2013 11.10.2013 20.10.2013..请将此添加到问题本身。这是u问题：order by datetime desc But；group by tax.parent=我正在解决问题，但是；group by tax.parent和order by datatime=他们是问题OP正在使用WordPress。这可能会使您当前的答案错误，而不管其潜在优点如何。

$post = $wpdb->get_results("SELECT `p`.`ID`, MAX(p.post_date) as `datetime`, `p`.`post_date`, `p`.`post_content`, `p`.`post_title`, `p`.`post_status`, `p`.`post_name`, `p`.`comment_count`, `tax`.`term_taxonomy_id`, `tax`.`term_id`, `tax`.`taxonomy`, `tax`.`parent`, `rel`.`object_id`, `rel`.`term_taxonomy_id`

FROM (`$wpdb->posts` AS p)

INNER JOIN `$wpdb->term_relationships` AS rel ON `rel`.`object_id` = `p`.`ID`

INNER JOIN `$wpdb->term_taxonomy` AS tax ON `tax`.`term_taxonomy_id` = `rel`.`term_taxonomy_id`

WHERE `tax`.`taxonomy` =  'category'AND `p`.`post_status` = 'publish' AND `p`.`post_type` =  'post'

GROUP BY tax.parent

ORDER BY datetime DESC LIMIT 4

");  

    select l.* 
    from table l
    inner join (
      select 
        m_id, max(timestamp) as latest 
      from table 
      group by m_id
    ) r
      on l.timestamp = r.latest and l.m_id = r.m_id
    order by timestamp desc

print your query and enter on phpmyadmin. we get exactly error . so you know easily what you want change