Most of the PHP I write runs on Bluemix - it's IBM self-service cloud, and since I work there, they pay for my accounts :) There are a bunch of databases you can use there, mostly open source offerings, and of course with PHP I like to use MySQL. Someone asked me for my connection code since it's a bit tricky to grab the credentials that you need, so here it is.
Bluemix Environment Variables
In Bluemix, you can simply create a MySQL database (look for "compose-for-mysql" in the catalog), create a set of credentials, and then bind it to your app. I should blog a few more of my PHP-on-Bluemix tricks but you can run a selection of PHP versions and it's also possible to add extensions that you need, I have found it does have what I need once I figure out how to configure it!
Once the database is bound to the application, then your PHP code
running on Bluemix will have an environment variable called