Contact management

I am working with a programmer and we have IntelliJ running a project that we wrote mostly in HTML, J2EE, and JS using IntelliJ. Since IntelliJ uses a MySQL database and we can access our local project from the internet, I thought it would be easy for us to do a new Contacts database that could run concurrently but we are running into trouble. We want to access the MySQL database that is running on the local system from another device.