[ADMIN] How do I give user access to database?

[someone]

I have created a database as user "dennis", because dennis has
permission to create databases.
I want to access it through a PHP script in a Web document, the web
server is running as user "nobody",
but user nobody does not have permission to use the database created by
dennis.  Nobody, cannot create
databases and I want it that way.  How do I give nobody permission to
use "dennis"s database.   Thanks.