MySQL表中的最新記錄

Question

如何從此表中選擇最新記錄（= MAX（order_history_id）（每個order_id一個[最新]行）：

+----------------+--------+-------+----------+
|order_history_id|order_id|trackc |date_added|
+----------------+--------+-------+----------+
|      4400      |   1000 | text  | 2014-9-24|
|      4401      |   1001 | text2 | 2014-9-26|
|      4410      |   1000 | text3 | 2014-9-29|
|      4411      |   1003 | text4 | 2014-9-20|
+----------------+--------+-------+----------+

我目前的查詢是：

SELECT * FROM order_history WHERE  trackc <>  '' GROUP BY order_id

Answer 1

select t1.* from order_history t1
inner join(
    select order_id,max(order_history_id) as order_history_id
    from order_history
    where ifnull(trackcode,'') <> ''
    group by order_id
) as t2 on t1.order_history_id = t2.order_history_id

Answer 2

SELECT * from order_history as oh inner join (
    SELECT MAX(order_history_id) AS max_id, order_id
    FROM order_history
    GROUP BY order_id
) as t ON t.max_id = oh.order_history_id
WHERE oh.trackc <>  ''

子查詢提取每個order_id的最大值。 比使用order_history連接找到的值並提取每個字段。

Answer 3

 select or.order_history_id,or.order_id,or.trackc,or.date_added From order_history or
 order by or.order_id Desc
 limit 1;