How to find "nearby" results?

Question

Assuming you have the latitude and longitude of your user, and you want to find nearby... let's say restaurants, how do you query your relational DB? For something like "restaurants within a 25 mile radius"?

Would you just query for restaurants in a square with a long and lat greater than/less than the user's loc +/- 25 miles (converted to degrees I guess), and then filter out the "corners" in whatever language your using? Or can/should you do it directly in the SQL?

Answer 1

Take a look at the spatial features available in oracle for instance - here is the wikipedia entry http://en.wikipedia.org/wiki/Spatial_query, and a link with examples from noaa https://www.ngdc.noaa.gov/wiki/index.php?title=Sample_Oracle_Spatial_Queries