postgresql 计算两点距离的2种方法小结

 select ST_Distance( ST_SetSRID(ST_MakePoint(115.97166453999147,28.716493914230423),4326)::geography, ST_SetSRID(ST_MakePoint(106.00231199774656,29.719258550486572),4326)::geography ), ST_Length( ST_MakeLine( ST_MakePoint(115.97166453999147,28.716493914230423), ST_MakePoint(106.00231199774656,29.719258550486572) )::geography )

 ST_GeomFromText('LINESTRING(115.97166453999147 28.716493914230423,106.00231199774656 29.719258550486572)')与 ST_MakeLine( ST_MakePoint(115.97166453999147,28.716493914230423), ST_MakePoint(106.00231199774656,29.719258550486572) )等价 ST_GeomFromText('POINT(115.97166453999147 28.716493914230423)',4326)与 ST_SetSRID(ST_MakePoint(115.97166453999147,28.716493914230423),4326)等价 ST_SetSRID(ST_MakePoint(115.97166453999147,28.716493914230423),4326)::geography与 Geography(ST_SetSRID(ST_MakePoint(115.97166453999147,28.716493914230423),4326))、 ST_GeographyFromText('SRID=4326;POINT(115.97166453999147 28.716493914230423)')等价 (::geography是postgis中的转换类型语法,把geometry转成geography)

 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;