谢谢大家解答！最后问题发现由于CI的特殊架构必须通过index.php才能运行cron。最后方法：*/5 * * * * php /var/www/html/index.php email_temporary

真正的问题是JQuery版本问题。我将JQuery降级到1.2.0版本后即可正常使用。

Problem solved. You cannot limit what the update function does. It will do the update for all rows in the table despite the foreach function. In order to accomplish the same objective, I've resorted to: