6

我有下表，

    mysql> select username,authdate from radpostauth;
+------------+---------------------+
| username   | authdate            |
+------------+---------------------+
| timetest   | 2013-05-21 22:44:46 |
| timetest   | 2013-05-21 23:54:20 |
| coconeja   | 2013-05-22 00:01:42 |
| coconeja   | 2013-05-22 00:06:35 |
| coconeja   | 2013-05-25 22:35:34 |
| timetest   | 2013-05-25 23:04:54 |
| distom11   | 2013-05-25 23:10:47 |
| distom11   | 2013-05-25 23:16:42 |
| test       | 2013-05-25 23:45:16 |
| pepe       | 2013-05-26 00:07:00 |
| doce       | 2013-05-26 00:46:48 |
| 6096753968 | 2013-05-26 01:42:30 |
| 2269664468 | 2013-05-26 01:43:57 |
| 2076877624 | 2013-05-26 02:01:53 |
| 4446830988 | 2013-05-26 02:02:28 |
| 2076877624 | 2013-05-26 02:08:53 |
| 3906187975 | 2013-05-26 22:00:30 |
| 3906187975 | 2013-05-26 22:21:44 |
| kk         | 2013-05-26 22:32:20 |
| kk         | 2013-05-26 22:44:19 |
| 160059817  | 2013-05-27 00:53:56 |
| yibced9    | 2013-05-27 13:32:00 |
| yibced9    | 2013-05-27 13:37:53 |
| yibced9    | 2013-05-27 13:38:01 |
| yibced9    | 2013-05-27 13:38:02 |
| yibced9    | 2013-05-27 13:38:03 |
| yibced9    | 2013-05-27 13:38:39 |
| yibced9    | 2013-05-27 13:38:40 |
| yibced9    | 2013-05-27 13:38:41 |
| yibced9    | 2013-05-27 13:44:40 |

我想找到在过去 12 小时内首次访问的“用户名”。

我知道如何获取每个用户第一次使用以下查询登录的时间

    mysql> select username,min(authdate) from radpostauth group by username;
+------------+---------------------+
| username   | min(authdate)       |
+------------+---------------------+
| 160059817  | 2013-05-27 00:53:56 |
| 2076877624 | 2013-05-26 02:01:53 |
| 2269664468 | 2013-05-26 01:43:57 |
| 3906187975 | 2013-05-26 22:00:30 |
| 4446830988 | 2013-05-26 02:02:28 |
| 6096753968 | 2013-05-26 01:42:30 |
| coconeja   | 2013-05-22 00:01:42 |
| distom11   | 2013-05-25 23:10:47 |
| doce       | 2013-05-26 00:46:48 |
| kk         | 2013-05-26 22:32:20 |
| pepe       | 2013-05-26 00:07:00 |
| test       | 2013-05-25 23:45:16 |
| timetest   | 2013-05-21 22:44:46 |
| yibced9    | 2013-05-27 13:32:00 |
+------------+---------------------+

所以现在我正在尝试让这些用户名这样做：

select *
from radpostauth
where (
    select username,min(authdate)
    from radpostauth group by username
    ) > timediff( now(),maketime(12,0,0,) );

但显然它不起作用......

4

2 回答 2

14 
select username, min(authdate) 
from radpostauth 
group by username
having min(authdate) > NOW() - INTERVAL 12 HOUR

在 SQL 中，WHERE 限制行，但 HAVING 限制组。

于 2013-05-27T20:57:36.927 回答
1

完美的答案是比尔在这里，但为了详尽无遗，大卫的尝试值得纠正：

SELECT *
FROM (
    SELECT username, MIN(authdate) as min_authdate
    FROM radpostauth
    GROUP BY username
) T
WHERE min_authdate > NOW() - INTERVAL 12 HOUR;
于 2013-05-27T21:24:32.390 回答