@ Zarathuztra convenient phpmyadmin is a tool to manage MySQL databases. What you need is a script on the server that receives the requests from the smartphone is making special thinks inside. Save or manipulates the data in the database and sends the result back on to the phone. This is not the opinion, we can teach you on StackOverflow, sorry.
Watch out for cloud database services to your problem on the internet or ask are PHP-coder for help.