地理坐标计算

/*根据半径（1000米）选择记录 */
SELECT * FROM pointlocation where earth_box(ll_to_earth(40.057031,116.307852),4000) @> ll_to_earth(pointlocation.lat, pointlocation.lon);

/*判两点间的距离*/
SELECT earth_distance(ll_to_earth(40.057031,116.307852), ll_to_earth(pointlocation.lat, pointlocation.lon)) FROM pointlocation where id=1112

 /*矩形范围查找*/

SELECT *
from pointlocation
where
ST_Contains(ST_MakePolygon(ST_GeomFromText('LINESTRING ( 116.845397 40.008134 , 116.221114 40.008134 ,116.245397 40.108134 , 116.245397 41.108134 , 116.845397 40.008134) ')) ,st_point(pointlocation.lon,pointlocation.lat))='t'

/*
* postgreSQL之earthdistance学习笔记
* author: wusuopubupt
* date: 2013-03-31
*/

/*创建表*/
CREATE TABLE picture (
  id serial PRIMARY KEY ,
  p_uid char(12) NOT NULL,
  p_key char(23) NOT NULL,
  lat real not null,
  lng real NOT NULL,
  up int NOT NULL,
  down int NOT NULL,
  ip varchar(15) DEFAULT NULL,
  address varchar(256) DEFAULT NULL
);

/*插入记录*/
INSERT INTO picture(p_uid, p_key, lat, lng, up, down, ip, address)
VALUES('aaaabbbbcccc', '2014032008164023279.png', 40.043945, 116.413668, 0, 0, '', '');

/*插入记录*/
INSERT INTO picture(p_uid, p_key, lat, lng, up, down, ip, address)
VALUES('xxxxccccmmmm', '2014032008164023111.png', 40.067183, 116.415230, 0, 0, '', '');

/*选择记录*/
SELECT * FROM picture;

/*更新记录*/
UPDATE picture SET address='LiShuiqiao' WHERE id=1;
UPDATE picture SET address='TianTongyuan' WHERE id=2;

/*对经纬度列创建索引*/
CREATE INDEX ll_idx on picture USING gist(ll_to_earth(lat, lng));

/*根据半径（1000米）选择记录*/
SELECT * FROM picture where earth_box(ll_to_earth(40.059286,116.418773),1000) @> ll_to_earth(picture.lat, picture.lng);

/*选择距离当前用户的距离*/
SELECT picture.id, earth_distance(ll_to_earth(picture.lat, picture.lng), ll_to_earth(40.059286,116.418773))
AS dis FROM picture
ORDER BY dis ASC;

/*
 * 以下内容是网上的一篇教程
 * 地址：http://www.cse.iitb.ac.in/dbms/Data/Courses/CS631/PostgreSQL-Resources/postgresql-9.2.4/contrib/earthdistance/expected/earthdistance.out
 */