本文介绍了mysql now函数的一个例子，在一条sql语句中多次引用now函数，显示相同的时间，感兴趣的朋友参考下.
例子，mysql sum函数用法举例。
Multiple references to a function such as NOW() within a single query always produce the same result
sql语句 如下：
mysql>
This principle also applies to CURDATE(), CURTIME(), UTC_DATE(), UTC_TIME(), UTC_TIMESTAMP(), and to any of their synonyms.
mysql>
mysql> select now(), now();
+---------------------+---------------------+
| now() | now() |
+---------------------+---------------------+
| 2007-07-22 19:46:01 | 2007-07-22 19:46:01 |
+---------------------+---------------------+
1 row in set (0.00 sec)
