I am searching for a skinny, generic layer (most likely designed in PHP) that sits from a database (most likely MySQL) and web service clients (that could be anything). I imagine there'd be config files of some kind that tell it how you can map web service demands to database queries (or any other DB instructions). It might should also handle authentication and authorization, obviously.

I have done some searching but unsuccessful to locate something that will do the job. Can anybody suggest something similar to this?

This is actually the right framework to your requirements - http://sourceforge.net/projects/phprestsql/

Well, you will find a variety of PHP database frameworks that might easily suit you perfectly.

Most apparent is PDO, that is really just some courses of instruction for dealing with the database. It's a part of PHP 5.1+ therefore it does not even need a download.

Other medication is more complete, and do a variety of meet your needs.

And check Google for any massively large list. Hope that can help.

phpMyAdmin may be what you're searching for.