I have installed WAMP because I am attempting to modify an an application which uses Zend Optimizer (I cannot use Z.O. with PHP5.3+, which is why I decided to install WAMP). I downloaded the latest version - Wamp Server 2.1 - which comes bundled with PHP5.3.5. I then downloaded a PHP version that would be compatible with Z.O. - 5.2.9. - and a compatible Apache version, 2.0.63.

My problem: PHP scripts run fine, but anything with MySQL does not work. Running the testmysql.php script returns the fatal error: Fatal error: Call to undefined function mysql_connect() in C:\wamp\www\testmysql.php on line 2".

I have looked in the PHP INI files inside both PHP versions, and I'm fairly sure the relevant information is there. At least, there are parts inside that mention MySQL! Perhaps somebody could clarify exactly what information should be present?

Also, when visiting a page that called phpinfo(), I noticed that the 'Loaded Configuration File' was pointing to C:\wamp\bin\php\php5.3.5\php.ini, even though I have enabled the older PHP version. I've stopped and started Apache, too, and that hasn't made a difference.

Is anybody able to offer any assistance? Anything at all would be great; I'm not very good at messing around with Apache/