下面是具体的实现代码：
sqlite> SELECT datetime(1377168853, 'unixepoch', 'localtime');
+------------------------------------------------+| datetime(1377168853, 'unixepoch', 'localtime') |+------------------------------------------------+| 2013-08-22 18:54:13 |+------------------------------------------------+1 row in setsqlite> SELECT strftime('%s','now');
+----------------------+| strftime('%s','now') |+----------------------+| 1380728519 |+----------------------+1 row in setsqlite> SELECT datetime('now');
+---------------------+| datetime('now') |+---------------------+| 2013-10-02 15:40:44 |+---------------------+1 row in set
