mysql - 查询每个用户最近登录到当前日期的日期

Question

我想询问一个示例查询，我可以用它来了解每个用户的最新登录日期...谢谢

+----+---------+------------+-----------+---------------------+
| id | version | first_name | last_name | login_detail        |
+----+---------+------------+-----------+---------------------+
|  1 |       0 | Mark       | Yap2      | 2013-02-01 16:00:23 |
|  2 |       0 | Mark       | Yap2      | 2013-02-01 16:00:38 |
|  3 |       0 | Mark       | Yap2      | 2013-02-04 13:38:41 |
|  4 |       0 | john       | doe       | 2013-02-04 13:50:39 |
|  5 |       0 | Mark       | Yap2      | 2013-02-04 13:59:01 |
|  6 |       0 | Mark       | Yap2      | 2013-02-04 14:04:25 |
|  7 |       0 | john       | doe       | 2013-02-04 14:09:47 |
|  8 |       0 | Mark       | Yap2      | 2013-02-04 14:14:40 |
|  9 |       0 | Mark       | Yap2      | 2013-02-04 14:15:36 |
| 10 |       0 | john       | doe       | 2013-02-04 14:16:11 |
| 11 |       0 | Mark       | Yap2      | 2013-02-04 14:23:38 |
| 12 |       0 | john       | doe       | 2013-02-04 14:26:53 |
| 13 |       0 | john       | doe       | 2013-02-04 15:50:45 |
| 14 |       0 | john       | doe       | 2013-02-04 15:55:53 |
| 15 |       0 | john       | doe       | 2013-02-04 15:59:15 |
| 16 |       0 | john       | doe       | 2013-02-04 16:05:15 |
| 17 |       0 | john       | doe       | 2013-02-04 16:09:54 |
+----+---------+------------+-----------+---------------------+

对于此示例表...我想获取每个用户的最新登录记录...对于 2 个不同的用户，这些记录的 ID 为 17 和 11

Answer 1

假设您有一个名为 的表tableName，并且有列：userID, last_login。MAX您可以通过使用which is a Aggregate Function来了解用户的最新登录日期。

SELECT userID, 
       MAX(last_login) most_current_login
FROM   tableName
GROUP  BY userID

Answer 2

询问：

SQLFIDDLE示例

SELECT first_name, 
       last_name,
       MAX(login_detail) latest_login_record
FROM   Table1
GROUP  BY first_name, 
          last_name

结果：

| FIRST_NAME | LAST_NAME |             LATEST_LOGIN_RECORD |
------------------------------------------------------------
|       john |       doe | February, 04 2013 16:09:54+0000 |
|       Mark |      Yap2 | February, 04 2013 14:23:38+0000 |