Hello
at first sorry for my English .....
After reading through the forum I see that the way to access mysql is not secure, and that posting on. Php du ser data and password does not give me much confidence ..
Connecting with a serverside script such as php is a very secure option in my opinion since you don't have to store and send the login credentials through the app.
If you are going to use a server side script like mysqltunnel.php you can always use an encrypted connection based on https, or use mysqltunnel's encryption feature based on a variable hash key.
Of course you can set the database credentials on the server side script, just to not transfer DB's password data over http.
Also if you have sensible data to transfer to/from device/DB then ecnryption would be needed again based on https or hash key.