将 Postgres 几何格式转换为 WKT

本文介绍了将 Postgres 几何格式转换为 WKT的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我有一个 Postgres 表，它在其中一列中以其特定格式存储多边形几何图形，就像这样-

0103000020E61000000100000004000000B8627F336B1554405DD602FFA2733A40B8627FA7601554403851F8EBC7723A40B8627FC38F15544036D539E90B733A40B8627F336B1554405DD602FFA2733A40

我知道如何使用 ST_AsText 将这个单个值转换为 WKT，这会给我 POLYGON((Lat Long)).但我想将整列转换为 WKT 格式.

如何实现这一目标?

谢谢！

解决方案

你试过了吗?

SELECT ST_AsText(your_geom_column) FROM your_table

在以下示例中，我将向您展示几种序列化几何的方法 - 两个点的数据样本编码为 4326 (WGS84):

CREATE TEMPORARY TABLE tmp (geom GEOMETRY);插入 tmp 值 ('SRID=4326;POINT (1 2)'),('SRID=4326;点 (2 4)');

几何图形为 WKB(默认):

SELECT geom FROM tmp;几何--------------------------------------------------——0101000020E6100000000000000000F03F00000000000000400101000020E610000000000000000000400000000000001040

几何为 WKT 和 EWKT(带有空间参考系统的 WKT):

SELECT ST_AsText(geom),ST_AsEWKT(geom) FROM tmp;st_astext |st_asewkt------------+----------------------点(1 2) |SRID=4326；点(1 2)点(2 4) |SRID=4326；点(2 4)

如果您喜欢 GeoJSON ..

SELECT ST_AsGeoJSON(geom) FROM tmp;st_asgeojson-------------------------------{类型":点"，坐标":[1,2]}{类型":点"，坐标":[2,4]}

.. 甚至 GML

SELECT ST_AsGML(geom) FROM tmp;st_asgml-----------------------------------------------------------------------------------<gml:Point srsName=EPSG:4326"><gml:coordinates>1,2</gml:coordinates></gml:Point><gml:Point srsName=EPSG:4326"><gml:coordinates>2,4</gml:coordinates></gml:Point>

... 谷歌地球爱好者也有他们的乐趣！几何图形为 KML

SELECT ST_AsKML(geom) FROM tmp;st_askml-----------------------------------------------<点><坐标>1,2</坐标></点><点><坐标>2,4</坐标></点>

名单还在继续……！在 PostGIS 文档 中，您会发现序列化几何图形的其他奇特方法.

演示:db<>fiddle

I have a Postgres table which stores polygon geometry in its specific format in one of the column, something like this-

0103000020E61000000100000004000000B8627F336B1554405DD602FFA2733A40B8627FA7601554403851F8EBC7723A40B8627FC38F15544036D539E90B733A40B8627F336B1554405DD602FFA2733A40

I know how to convert this single value to WKT using ST_AsText which will give me POLYGON((Lat Long)). But I want to convert whole column into WKT format.

How to achieve this?

Thanks!

解决方案

Have you tried this?

SELECT ST_AsText(your_geom_column) FROM your_table

In the following examples I'll show you a few ways to serialise your geometries - data sample with two points encoded as 4326 (WGS84):

CREATE TEMPORARY TABLE tmp (geom GEOMETRY);
INSERT INTO tmp VALUES ('SRID=4326;POINT (1 2)'),
                       ('SRID=4326;POINT (2 4)');

Geometries as WKB (default):

SELECT geom FROM tmp;
                        geom
----------------------------------------------------
 0101000020E6100000000000000000F03F0000000000000040
 0101000020E610000000000000000000400000000000001040

Geometries as WKT and EWKT (a WKT with the Spatial Reference System):

SELECT ST_AsText(geom),ST_AsEWKT(geom) FROM tmp;
 st_astext  |      st_asewkt
------------+----------------------
 POINT(1 2) | SRID=4326;POINT(1 2)
 POINT(2 4) | SRID=4326;POINT(2 4)

In case you fancy GeoJSON ..

SELECT ST_AsGeoJSON(geom) FROM tmp;
             st_asgeojson
--------------------------------------
 {"type":"Point","coordinates":[1,2]}
 {"type":"Point","coordinates":[2,4]}

.. or even GML

SELECT ST_AsGML(geom) FROM tmp;
                                     st_asgml
-----------------------------------------------------------------------------------
 <gml:Point srsName="EPSG:4326"><gml:coordinates>1,2</gml:coordinates></gml:Point>
 <gml:Point srsName="EPSG:4326"><gml:coordinates>2,4</gml:coordinates></gml:Point>

.. the Google Earth enthusiasts also have their fun! Geometries as KML

SELECT ST_AsKML(geom) FROM tmp;
                   st_askml
-----------------------------------------------
 <Point><coordinates>1,2</coordinates></Point>
 <Point><coordinates>2,4</coordinates></Point>

And the list goes on..! In the PostGIS documentation you will find other fancy ways to serialise your geometries.

Demo: db<>fiddle

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