我正在尝试从用户保留表中获取一些数据。我的用户名单如下：
+----+-------------+--------------+----------------------------+------------+--------+
| id | Qty_holding | Qty_reserved | created | tokenid_id | uid_id |
+----+-------------+--------------+----------------------------+------------+--------+
| 1 | 10 | 0 | 2018-01-18 10:52:14.957027 | 1 | 1 |
| 2 | 20 | 0 | 2018-01-18 11:20:08.205006 | 8 | 1 |
| 3 | 110 | 0 | 2018-01-18 11:20:21.496318 | 14 | 1 |
| 4 | 10 | 0 | 2018-01-23 14:26:49.124607 | 1 | 2 |
| 5 | 3 | 0 | 2018-01-23 15:00:26.876623 | 11 | 2 |
| 6 | 7 | 0 | 2018-01-23 15:08:41.887240 | 11 | 2 |
| 7 | 11 | 0 | 2018-01-23 15:22:48.424224 | 11 | 2 |
| 8 | 15 | 0 | 2018-01-23 15:24:03.419907 | 11 | 2 |
| 9 | 19 | 0 | 2018-01-23 15:24:26.531141 | 11 | 2 |
| 10 | 23 | 0 | 2018-01-23 15:27:11.549538 | 11 | 2 |
| 11 | 27 | 0 | 2018-01-23 15:27:24.162944 | 11 | 2 |
| 12 | 7.7909428 | 0.11459088 | 2018-01-23 15:27:24.168643 | 1 | 2 |
| 13 | 3 | 0 | 2018-01-23 15:36:51.412340 | 14 | 2 |
| 14 | 7.5585988 | 0.11459088 | 2018-01-23 15:36:51.417177 | 1 | 2 |
| 15 | 6 | 0 | 2018-01-24 08:43:46.635069 | 14 | 2 |
| 16 | 7.3262548 | 0.11459088 | 2018-01-24 08:43:46.639984 | 1 | 2 |
| 17 | 9 | 0 | 2018-01-24 10:09:08.207816 | 14 | 2 |
| 18 | 7.0939108 | 0.11459088 | 2018-01-24 10:09:08.212842 | 1 | 2 |
| 19 | 6 | 3 | 2018-01-24 13:43:08.929586 | 14 | 2 |
| 20 | 3 | 6 | 2018-01-24 14:49:56.960112 | 14 | 2 |
| 21 | 0 | 9 | 2018-01-24 14:50:33.423671 | 14 | 2 |
| 22 | 30 | 9 | 2018-01-24 14:51:14.865453 | 14 | 2 |
| 23 | 4.7704708 | 0.11459088 | 2018-01-24 14:51:14.870256 | 1 | 2 |
| 24 | 27 | 12 | 2018-01-24 14:56:56.914009 | 14 | 2 |
| 25 | 24 | 15 | 2018-01-24 14:57:56.475939 | 14 | 2 |
| 26 | 21 | 15 | 2018-01-24 14:58:06.750903 | 14 | 2 |
| 27 | 18 | 15 | 2018-01-24 15:02:43.203878 | 14 | 2 |
| 28 | 4.7705074 | 0.11459088 | 2018-01-24 15:02:43.224901 | 1 | 2 |
| 29 | 24 | 0 | 2018-01-24 15:03:40.421943 | 11 | 2 |
| 30 | 4.9535074 | 0.11459088 | 2018-01-24 15:03:40.441552 | 1 | 2 |
| 31 | 1 | 0 | 2018-01-26 10:35:33.173801 | 18 | 2 |
+----+-------------+--------------+----------------------------+------------+--------+
我必须找到每个用户的每个令牌的最新Qty_holding。我想尝试：
mysql> select uid_id,tokenid_id,Qty_holding from accounts_userholding group by uid_id,tokenid_id order by created desc;
它给出了以下结果：
+--------+------------+-------------+
| uid_id | tokenid_id | Qty_holding |
+--------+------------+-------------+
| 2 | 18 | 1 |
| 2 | 14 | 3 |
| 2 | 11 | 3 |
| 2 | 1 | 10 |
| 1 | 14 | 110 |
| 1 | 8 | 20 |
| 1 | 1 | 10 |
+--------+------------+-------------+
此结果中的问题是Qty_holding不是最新的。另外，我正在尝试编写等效的Django查询，如下所示：
UserHolding.objects.values('tokenid_id','uid_id','Qty_holding').order_by().annotate(Count('tokenid_id'),Count('uid_id'))
任何帮助将不胜感激。
答案 0 :(得分：2)
您可以使用子查询
来完成select t1.*
from accounts_userholding t1
join
(
select uid_id, tokenid_id, max(created) as max_created
from accounts_userholding
group by uid_id, tokenid_id
) t2 on t1.uid_id = t2.uid_id
and t1.tokenid_id = t2.tokenid_id
and t1.created = t2.max_created
答案 1 :(得分：1)
您必须获取每个tokenid_id和uid_id的最新ID，并使用此ID过滤掉结果，如下所示：
SELECT
A.tokenid_id, A.uid_id, A.Qty_holding
FROM accounts_userholding A LEFT JOIN
(SELECT tokenid_id, uid_id, MAX(id) id FROM accounts_userholding GROUP BY tokenid_id, uid_id) B
ON A.id=B.id;