SQL to find distance from latitude/longitude

This is a quick post, mostly so i never forget this. A guy I work with either wrote this or found it on the internet. If you have a database of addresses with lat/long pairs for each entry, this SQL statement will find the distance (I think in miles) from a given lat/long.

SELECT 
    ( 3959 * acos( cos( radians(origin_lat) ) * cos( radians( latitude ) ) * cos( radians( longitude ) - radians(origin_long) ) + sin( radians(origin_lat) ) * sin( radians( latitude ) ) ) ) AS distance 
FROM
    zip_codes
HAVING
    distance <= _miles
ORDER BY
    zip;