MySQL：MAX不返回

Question

如何獲得按最大列排序並按ID分組的行列表？我始終得到正確的最大值，但其他字段是從其他行獲得的。

我使用了以下內容：

SELECT p.* 
      FROM `logs` AS p 
      JOIN 
      (SELECT person_id, 
      MAX(`datetime`) AS datetime 
      FROM `logs` 
      GROUP BY `person_id` 
      ) AS pg 
      ON pg.person_id = p.person_id 
      AND pg.`datetime` = p.datetime 
      group by person_id 

哪裏是我的查詢錯了嗎？日期時間和人員ID總是正確的，但其他字段不是。

Answer 1

看到這個：http://bugs.mysql.com/bug.php?id=54784

Answer 2

SELECT MIN（日期時間）並不總是返回最小的日期時間 值。與MAX相同。

臨時解決方法：

 SELECT p.* 
     FROM `logs` AS p 
     JOIN 
       (SELECT person_id, 
         MAX(CAST(`datetime` as CHAR(25))) AS `datetime` 
       FROM `logs` 
       GROUP BY `person_id` 
       ) AS pg 
        ON pg.person_id = p.person_id AND 
       pg.`datetime` = p.datetime 
     group by person_id 

Answer 3

請嘗試以下：

SELECT logs.* 
    FROM (SELECT person_id, 
      MAX(`datetime`) AS latest 
      FROM `logs` 
     GROUP BY person_id) AS dt 
INNER 
    JOIN logs 
    ON logs.person_id= dt.person_id 
    AND logs.datetime= dt.latest