Do not access the SQL directly there is no need and it adds complexity and dependencies to your app.

Use https to access the web frontend and at the very least use a hash to verify the POSTs, example:

name=Foobar
score=3489437
md5=<md5 of name, score and a secret string known to the app and the server>

Of course for open source software the secret isn't one much longer (and https protects just from casual network sniffing) and disassembly is always possible.

This is actually pretty hard problem to solve if supposing the attackers have resources and interest to throw at it.