PHP date()函数警告: It is not safe to rely on the system解

PHP Warning:  date(): It is not safe to rely on the system's timezone settings. You are required to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still gett
ing this warning, you most likely misspelled the timezone identifier. We selected 'Asia/Chongqing' for 'CST/8.0/no DST' instead in /data0/htdocs/.qttc./function/function.php on line 542

date_default_timezone_set("PRC");