Enable MySQL support in PHP5/Win32/Apache2
There have one stupid thing where is nobody know. After you set the ext path and un-comment the modules in c:\windows\php.ini , you should also copy libmysql into windows directory. Otherwise you will get this message in apache log.
PHP Warning: PHP Startup: Unable to load dynamic library ‘c:\\php\\ext\\php_mysqli.dll’ – The specified module could not be found.\r\n in Unknown on line 0