So, I want to know how to do that, and I pretty
Since an Android application cannot connect directly to a MySQL server you need to write a kind of a "bridge".
UPDATE: @see Femi's comment
Well, technically speaking, It could: http://developer.android.com/reference/javax/sql/package-summary.html
But for security reasons a bridge is a mandatory choice IMHO.
One one the most popular approach is to use the http protocol for sending and reading data.
Your city.php will contain the logic for connect and querying the
database:
The Android app will connect trough your server and will parse the json output.
So yes, you need to write the server-side part and client side part (Android)
A really useful video: http://www.google.com/events/io/2010/sessions/developing-RESTful-android-apps.html
Code sample with PHP as bridge and Android via http protocol:
http://www.helloandroid.com/tutorials/connecting-mysql-database