location based search

geo.sql

SELECT 
    dest.sn,
    dest.ort,
	dest.kreis,
	ACOS(
         SIN(RADIANS(src.lat)) * SIN(RADIANS(dest.lat)) 
         + COS(RADIANS(src.lat)) * COS(RADIANS(dest.lat))
         * COS(RADIANS(src.lon) - RADIANS(dest.lon))
    ) * 6380 AS distance
FROM
    opengeodb dest
        CROSS JOIN
    opengeodb src
WHERE
    src.sn= 3541
        AND dest.sn <> src.sn
HAVING distance < 10
ORDER BY distance;

http://opengeodb.org/wiki/OpenGeoDB_-_Umkreissuche#Orte_im_Umkreis_ermitteln