To clarify, you cannot use PHP in the mobile app itself but you can certainly use it on the backend to connect to your database. An alternative is to use a Java EE backend.
if you wish to use a Java EE backend, we already have server connectors within MyEclipse that you can use. However, for PHP, you will need to install the PDT (PHP development tooling) so that you can develop the PHP based backend within MyEclipse and install a PHP server.
As far as connecting to a database is concerned, we have drivers that will allow you to connect to MySQL and automatically generate code for you in the case of a Java EE application. Unfortunately we do not have automated tooling for DB connections in the PHP space.
Hope this helps.