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;