Use the Haversine Formula to calculate the distance between two points on a sphere (like the earth!).
I had a similar problem where I had to calculate multiple distances from events (50km, 100km, 500km) - Using the Pythagorean theorem is fine for small distances but can produce some odd results for larger distances. This might help: https://code.google.com/apis/maps/articles/phpsqlsearch.html#findnearsql Finding locations nearby with MySQL To find locations in our markers table that are within a certain radius distance of a given latitude/longitude, you can use a SELECT statement based on the Haversine formula. The Haversine formula is used generally for computing great-circle distances between two pairs of coordinates on a sphere. An in-depth mathemetical explanation is given by Wikipedia and a good discussion of the formula as it relates to programming is on Movable Type's site. Here's the SQL statement that will find the closest 20 locations that are within a radius of 25 miles to the 37, -122 coordinate. It calculates the distance based on the latitude/longitude of that row and the target latitude/longitude, and then asks for only rows where the distance value is less than 25, orders the whole query by distance, and limits it to 20 results. To search by kilometers instead of miles, replace 3959 with 6371. SELECT id, ( 3959 * acos( cos( radians(37) ) * cos( radians( lat ) ) * cos( radians( lng ) - radians(-122) ) + sin( radians(37) ) * sin( radians( lat ) ) ) ) AS distance FROM markers HAVING distance < 25 ORDER BY distance LIMIT 0 , 20; On Apr 20, 8:24 am, Andi <[email protected]> wrote: > I have a database ,and now I have to show all the points that are at 5 km > distance from the current location, how can I do this? -- You received this message because you are subscribed to the Google Groups "Google Maps API For Flash" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-maps-api-for-flash?hl=en.
