# 通过设置系统变量“timestamp”。要再次将其恢复为当前时间戳，请将其设置为默认值。
mysql> SET TIMESTAMP = UNIX_TIMESTAMP('2015-01-01');
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT NOW();
+---------------------+
| NOW()               |
+---------------------+
| 2015-01-01 00:00:00 |
+---------------------+
1 row in set (0.00 sec)

mysql> SET TIMESTAMP = DEFAULT;
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT NOW();
+---------------------+
| NOW()               |
+---------------------+
| 2016-03-08 09:50:16 |
+---------------------+
1 row in set (0.00 sec)