I have to develop an algorithm for location based data grabbing and displaying it on a mobile device. I'm just a web programmer with some knowledge of php and mysql. I need to develop this algorithm. Please give some instructions on where to start the development.
You could have PointOfInterest table that relates to address. Let say I want to find an ATM in Chicago. Then you perform a seach for all ATMs in chicago. After you get your result set you perform distance calculation over each of them and check which is the closest one.
Here you may find a way how to calculate distance based on longitude/latitude coordinates