原文：http://blog.csdn.net/changzhi1990/article/details/40983247
php -m
输出：
PHP Warning: PHP Startup: Unable to load dynamic library './mysqli.so' - ./mysqli.so: cannot open shared object file: No such file or directory in Unknown on line 0
没有载入扩展。
vi /etc/php.ini
去除注释，并设置为：extension_dir =#查看是否有mysqli.so cd /usr/lib64/php/modules/ #没有则安装 yum install php-mysql