ST_AsEWKB
更新時(shí)間:
返回給定Geometry對象或Geography對象的WKB表示,其中包含SRID元數(shù)據(jù)信息。
語法
bytea ST_AsEWKB(geometry g1);
bytea ST_AsEWKB(geometry g1 , text NDRorXDR);
bytea ST_AsEWKB(geography g1);
bytea ST_AsEWKB(geography g1 , text NDRorXDR);
參數(shù)
參數(shù)名稱 | 描述 |
g1 | 目標(biāo)Geometry或Geography對象。 |
NDRorXDR | Little endian或Big endian,機(jī)器字節(jié)序。使用大端在前還是小端在前,默認(rèn)使用小端在前。
|
描述
標(biāo)準(zhǔn)WKB規(guī)范不包括SRID。要獲取具有SRID的WKB對象,請使用本函數(shù)。
該函數(shù)支持Circular Strings、Curves、Polyhedral surfaces、Triangles、Triangulated Irregular Network Surfaces(TIN)和3D對象。
示例
默認(rèn)使用小端在前,示例如下:
SELECT ST_AsEWKB(ST_GeomFromText('POLYGON((1 1,1 2,2 2,2 1,1 1))',4326)); st_asewkb --------------------------------------------------------------- \x0103000020e61000000100000005000000000000000000f03f000000000. .000f03f000000000000f03f00000000000000400000000000000040000000. .00000000400000000000000040000000000000f03f000000000000f03f000. .000000000f03f (1 row)
指定大端在前,示例如下:
SELECT ST_AsEWKB(ST_GeomFromText('POLYGON((1 1,1 2,2 2,2 1,1 1))',4326),'XDR'); st_asewkb --------------------------------------------------------------- \x0020000003000010e600000001000000053ff00000000000003ff000000. .00000003ff000000000000040000000000000004000000000000000400000. .000000000040000000000000003ff00000000000003ff00000000000003ff. .0000000000000 (1 row)
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