Php mysql order by datetime desc

Question

帖子圖表;

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

term_relationships Chart;

object_id term_taxonomy_id term_order 

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

term_taxonomy Chart;

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 

-

$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 

"); 

tax.parent =暢銷類別ID POST_DATE型數據類型

ORDER BY日期時間DESC =不正確排序:(

Answer 1

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 

Answer 2

嘗試附表別名:: OREDER BY p.post_date DESC