The mysqli extension is missing - centos servers

Even after enabling the service mysql and apache from the gui

You can try this in a root console:
rpm -qa | grep php-mysql
I think it should return something like this:
php-mysql-5.1.6-23.2.el5_3
if there is no return, the module is not installed;
yum install php-mysql - or use package manager if you installed the gnome gui.
then restart apache (httpd).

SEE ALSO http://itdrafts.blogspot.com/2011/10/blank-page-centos-lamp.html

Source:http://wordpress.org/support/topic/centos-53-problems-missing-the-mysql-extension