描述

使用小端(NDR)或大端(XDR)编码返回HEXEWKB格式(文本形式)的几何图形。如果未指定编码，则使用NDR。

	可用性：1.2.2

This function supports 3d and will not drop the z-index.

This method supports Circular Strings and Curves

示例

SELECT ST_AsHEXEWKB(ST_GeomFromText('POLYGON((0 0,0 1,1 1,1 0,0 0))',4326));
                which gives same answer as

                SELECT ST_GeomFromText('POLYGON((0 0,0 1,1 1,1 0,0 0))',4326)::text;

                st_ashexewkb
                --------
                0103000020E6100000010000000500
                00000000000000000000000000000000
                00000000000000000000000000000000F03F
                000000000000F03F000000000000F03F000000000000F03
                F000000000000000000000000000000000000000000000000