一、认识

来自网络的图片：

方案一：(来自网络)

postgresql计算两点欧式距离(经纬度地理位置)

create or replace function getdistance

(

lon1 numeric,

lat1 numeric,

lon2 numeric,

lat2 numeric

)

returns int

as

$body$

declare

v_distance numeric;

v_earth_radius numeric;

radLat1 numeric;

radLat2 numeric;

v_radlatdiff numeric;

v_radlngdiff numeric;

begin

--地球半径

v_earth_radius:=6378137;

radLat1 := lat1 * pi()/180.0;

radLat2 := lat2 * pi()/180.0;

v_radlatdiff := radLat1 - radLat2;

v_radlngdiff := lon1 * pi()/180.0 - lon2 * pi()/180.0;

v_distance := 2 * asin(sqrt(power(sin(v_radlatdiff / 2), 2) + cos(radLat1) * cos(radLat2) * power(sin(v_radlngdiff/2),2)));

v_distance := round(v_distance * v_earth_radius);

return v_distance;

end;

$body$

language 'plpgsql' volatile;

create or replace function getdistance

(

i_lngbegin real,

i_latbegin real,

i_lngend real,

i_latend real

)

returns float

as

$body$

/*

*

* select getdistance_bygispoint(116.281524,39.957202,117.648673,38.42584) as distance;

* */

declare

v_distance real;

v_earth_radius real;

v_radlatbegin real;

v_radlatend real;

v_radlatdiff real;

v_radlngdiff real;

begin

--地球半径

v_earth_radius:=6378.137;

v_radlatbegin := i_latbegin * pi()/180.0;

v_radlatend := i_latend * pi()/180.0;

v_radlatdiff := v_radlatbegin - v_radlatend;

v_radlngdiff := i_lngbegin * pi()/180.0 - i_lngend * pi()/180.0;

v_distance := 2 * asin(sqrt(power(sin(v_radlatdiff / 2), 2) + cos(v_radlatbegin) * cos(v_radlatend) * power(sin(v_radlngdiff/2),2)));

v_distance := v_distance * v_earth_radius*1000;

return v_distance;

end;

$body$

language 'plpgsql' volatile;

方案二：