Share database between app and web

I'm involved into an app that have to retrieve queries from an existing database. This db have to be implemented in php in a remote server, and will be the place where the admin will have to insert content into the shared db, but I don't know how to implement that correctly or what is the best solution.

I'm thinking about make a sqlite database with php and connect directly the app to the db, but I haven't found yet the best way to do that.

What do you think? Thank guys.