PHP is a server processed scripting language using the CGI model. Converting a DBP or WD site to use php is as simple as changing the extension to php and embedding <?php ?> sections containing code. You can even do the PHP in placeholders on different layers to make it easier within the software.
The only issues with WD and DBP is you gotta change the extensions post-export, and use CSS overflow-y:auto; property on placeholder DIVs. If you don't like ugly scrollbars don't bother though, and don't bother asking for dynamic placeholders even though the feature is a lot easier to implement then a lot of the stuff they keep implementing in releases and has been requested a trillion times.
HINT: use XAMPP for local testing, it can also be done inside the software