用PostgreSQL数据库做地理位置app应用

/*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
 */
--
--  Test earthdistance extension
--
-- In this file we also do some testing of extension create/drop scenarios.
-- That's really exercising the core database's dependency logic, so ideally
-- we'd do it in the core regression tests, but we can't for lack of suitable
-- guaranteed-available extensions.  earthdistance is a good test case because
-- it has a dependency on the cube extension.
--
CREATE EXTENSION earthdistance;  -- fail, must install cube first
ERROR:  required extension "cube" is not installed
CREATE EXTENSION cube;
CREATE EXTENSION earthdistance;
--
-- The radius of the Earth we are using.
--
SELECT earth()::numeric(20,5);
     earth    
---------------
 6378168.00000
(1 row)

--
-- Convert straight line distances to great circle distances.把直线距离转成大圆距离
--
SELECT (pi()*earth())::numeric(20,5);
    numeric    
----------------
 20037605.73216
(1 row)

SELECT sec_to_gc(0)::numeric(20,5);
 sec_to_gc
-----------
   0.00000
(1 row)

--
-- Convert great circle distances to straight line distances.
--
SELECT gc_to_sec(0)::numeric(20,5);
 gc_to_sec
-----------
   0.00000
(1 row)

SELECT gc_to_sec(sec_to_gc(2*earth()))::numeric(20,5);
   gc_to_sec   
----------------
 12756336.00000
(1 row)

--
-- Set coordinates using latitude and longitude.
-- Extract each coordinate separately so we can round them.
--
SELECT cube_ll_coord(ll_to_earth(0,0),1)::numeric(20,5),
 cube_ll_coord(ll_to_earth(0,0),2)::numeric(20,5),
 cube_ll_coord(ll_to_earth(0,0),3)::numeric(20,5);
 cube_ll_coord | cube_ll_coord | cube_ll_coord
---------------+---------------+---------------
 6378168.00000 |       0.00000 |       0.00000
(1 row)

SELECT cube_ll_coord(ll_to_earth(360,360),1)::numeric(20,5),
 cube_ll_coord(ll_to_earth(360,360),2)::numeric(20,5),
 cube_ll_coord(ll_to_earth(360,360),3)::numeric(20,5);
 cube_ll_coord | cube_ll_coord | cube_ll_coord
---------------+---------------+---------------
 6378168.00000 |       0.00000 |       0.00000
(1 row)

--
-- Test getting the latitude of a location.
--
SELECT latitude(ll_to_earth(0,0))::numeric(20,10);
   latitude  
--------------
 0.0000000000
(1 row)

SELECT latitude(ll_to_earth(45,0))::numeric(20,10);
   latitude   
---------------
 45.0000000000
(1 row)

--
-- Test getting the longitude of a location.
--
SELECT longitude(ll_to_earth(0,0))::numeric(20,10);
  longitude  
--------------
 0.0000000000
(1 row)

SELECT longitude(ll_to_earth(45,0))::numeric(20,10);
  longitude  
--------------
 0.0000000000
(1 row)

--
-- For the distance tests the following is some real life data.
--
-- Chicago has a latitude of 41.8 and a longitude of 87.6.
-- Albuquerque has a latitude of 35.1 and a longitude of 106.7.
-- (Note that latitude and longitude are specified differently
-- in the cube based functions than for the point based functions.)
--
--
-- Test getting the distance between two points using earth_distance.
--
SELECT earth_distance(ll_to_earth(0,0),ll_to_earth(0,0))::numeric(20,5);
 earth_distance
----------------
        0.00000
(1 row)

SELECT earth_distance(ll_to_earth(0,0),ll_to_earth(0,180))::numeric(20,5);
 earth_distance
----------------
 20037605.73216
(1 row)

--
-- Test getting the distance between two points using geo_distance.
--
SELECT geo_distance('(0,0)'::point,'(0,0)'::point)::numeric(20,5);
 geo_distance
--------------
      0.00000
(1 row)

SELECT geo_distance('(0,0)'::point,'(180,0)'::point)::numeric(20,5);
 geo_distance
--------------
  12436.77274
(1 row)

--
-- Test getting the distance between two points using the <@> operator.
--
SELECT ('(0,0)'::point <@> '(0,0)'::point)::numeric(20,5);
 numeric
---------
 0.00000
(1 row)

SELECT ('(0,0)'::point <@> '(180,0)'::point)::numeric(20,5);
   numeric  
-------------
 12436.77274
(1 row)

--
-- Test for points that should be in bounding boxes.
--
SELECT earth_box(ll_to_earth(0,0),
       earth_distance(ll_to_earth(0,0),ll_to_earth(0,1))*1.00001) @>
       ll_to_earth(0,1);
 ?column?
----------
 t
(1 row)

SELECT earth_box(ll_to_earth(0,0),
       earth_distance(ll_to_earth(0,0),ll_to_earth(0,0.1))*1.00001) @>
       ll_to_earth(0,0.1);
 ?column?
----------
 t
(1 row)

--
-- Test for points that shouldn't be in bounding boxes. Note that we need
-- to make points way outside, since some points close may be in the box
-- but further away than the distance we are testing.
--
SELECT earth_box(ll_to_earth(0,0),
       earth_distance(ll_to_earth(0,0),ll_to_earth(0,1))*.57735) @>
       ll_to_earth(0,1);
 ?column?
----------
 f
(1 row)

SELECT earth_box(ll_to_earth(0,0),
       earth_distance(ll_to_earth(0,0),ll_to_earth(0,0.1))*.57735) @>
       ll_to_earth(0,0.1);
 ?column?
----------
 f
(1 row)