データベーステーブル内の特定のIDの最新の行を取得するにはどうすればよいですか?

+----+---------------------+---------+
| id | signin              | signout |
+----+---------------------+---------+
|  1 | 2011-12-12 09:27:24 | NULL    |
|  1 | 2011-12-13 09:27:31 | NULL    |
|  1 | 2011-12-14 09:27:34 | NULL    |
|  2 | 2011-12-14 09:28:21 | NULL    |
+----+---------------------+---------+

SELECT 
 id, 
 MAX(signin) AS most_recent_signin
FROM tbl
GROUP BY id

SELECT 
  tbl.id,
  signin,
  signout
FROM tbl
  INNER JOIN (
    SELECT id, MAX(signin) AS maxsign FROM tbl GROUP BY id
  ) ms ON tbl.id = ms.id AND signin = maxsign
WHERE tbl.id=1