举例
==================================================

创建用户轨迹表
----------------------------------------

.. code-block:: sql

    CREATE TABLE user_loc (
        id serial PRIMARY KEY ,
        user_id bigint not NULL ,
        geom geometry(Point,4326) not NULL ,
        crt_time timestamp DEFAULT current_timestamp
    );


创建围栏表
----------------------------------------

.. code-block:: sql

    CREATE TABLE fence(
        id serial PRIMARY KEY ,
        name varchar(50),
        fence geometry(Polygon,4326),
        crt_time timestamp DEFAULT current_timestamp
    );


插入一个GPS坐标
----------------------------------------
.. code-block:: sql

    INSERT INTO user_loc(user_id,geom) VALUES (1,ST_GeomFromText('POINT(104.075476 30.542983)',4326));

插入电子围栏记录
----------------------------------------
.. code-block:: sql

    INSERT INTO fence(name,fence) values ('天府软件园',ST_MakePolygon( ST_GeomFromText('LINESTRING(104.063403 30.548403 , 104.063403 30.544142 ,104.069493 30.54408 , 104.073356 30.541669 , 104.075656 30.541607, 104.075332 30.548325, 104.063403 30.548403)',4326) ));

注意：第一个坐标点和最后一个坐标点必须一样。

判断点是否在多边形内
----------------------------------------

.. code-block:: sql

    SELECT  ST_Contains( ST_MakePolygon(ST_GeomFromText('LINESTRING ( 104.063403 30.548403 , 104.063403 30.544142 ,104.069493 30.54408 , 104.073356 30.541669 , 104.075656 30.541607, 104.075332 30.548325 ) ', 4326)) ,st_point(104.072601 30.54537) )


判断用户坐标是否在电子围栏内
----------------------------------------

.. code-block:: sql

    SELECT ST_Contains(
        (SELECT fence FROM fence WHERE id=1)
        ,
        ST_GeomFromText('POINT(104.069474 30.574392)', 4326)
    );