在没有配置，尤其是新安装的PHP中使用date函数时，会报这个错误：
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 getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in /usr/local/apache/htdocs/testsql.php on line 2
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 getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in /usr/local/apache/htdocs/testsql.php on line 3
这是因为，使用5.3以上版本时，没有正确的配置php.ini
解决方案如下：
vim /usr/local/php/etc/php.ini
找到timezone，去掉注释，并设置时区，在等于号后面加上Asia/Shanghai