title: Find long/lat's within 20 miles of user's long/lat
body: <p>I'm working on an application where a user can search for items near his location.</p>
  
  <p>When a user registers for my service, their long/lat coordinates are taken (this is actually grabbed from a zip/postcode and then gets looked up via Google for the long/lats). This also happens when a user adds an item, they are asked for the zip/postcode of the item, and that is converted to the long/lat.</p>
  
  <p>My question is how would i run a query using MySQL that would search within, say 20 miles, from the user's location and get all the items within that 20 mile radius?</p>