PostgreSQL latitude longitude query

Question

i have latitude and longitude columns in location table in PostgreSQL database, and I am trying to execute distance query with a Postg

Answer 1

An alternate Haversine formula, returning miles. (source)

CREATE OR REPLACE FUNCTION public.geodistance(
    latitude1 double precision,
    longitude1 double precision,
    latitude2 double precision,
    longitude2 double precision)
  RETURNS double precision AS
$BODY$
SELECT asin(
  sqrt(
    sin(radians($3-$1)/2)^2 +
    sin(radians($4-$2)/2)^2 *
    cos(radians($1)) *
    cos(radians($3))
  )
) * 7926.3352 AS distance;
$BODY$
  LANGUAGE sql IMMUTABLE
  COST 100;