我有2个表格,假设这是数据:
用户表:
------------------------------
| user_id | username |
------------------------------
| 1 | danny |
| 2 | george |
| 3 | lana |
| 4 | kim |
| 5 | tim |
------------------------------
用户登录表:
-----------------------------------------------
| record_id | user_id | recorder |
-----------------------------------------------
| 1 | 3 | 2012-11-06 04:18:26 |
| 2 | 3 | 2012-11-06 04:31:05 |
| 3 | 2 | 2012-11-06 03:44:22 |
| 4 | 1 | 2012-11-06 04:18:58 |
| 5 | 1 | 2012-11-06 04:30:15 |
| 6 | 3 | 2012-11-06 04:31:05 | X
| 7 | 1 | 2012-11-06 05:53:47 |
| 8 | 1 | 2012-11-06 05:55:15 | X
| 9 | 4 | 2012-11-06 05:59:31 |
| 10 | 4 | 2012-11-06 06:12:55 | X
-----------------------------------------------
我想展示最近3个登录的用户,所以结果只会显示标有"X"的行,或者说是独特的最近登录。
查询应该长什么样子?