Its hard to say how to do this specifically, but here is a high level. When they pick the initial location, you'll need to get the latitude and longitude. Then you need to see how much 1 mile corresponds to in latitude longitude. Using that measurement, you can get a range of acceptable latitude longitude values for your mile radius. Using this range, you would have to devise a database query that finds all results with a location falling inside your 1 mile range. I think something like that would do that trick.