$lat = 48.833297;
$lng = 2.298454;
// pour des miles : 3959
// pour des km : 6371
$sql = 'SELECT
name,
( 6371 * acos( cos( radians('.$lat.') ) * cos( radians( locations.lat ) )
* cos( radians(locations.lng) - radians('.$lng.')) + sin(radians('.$lat.'))
* sin( radians(locations.lat)))) AS distance
FROM locations
WHERE active = 1
HAVING distance < 10
ORDER BY distance'