ST_GEOMETRYFROMTEXT
描述
将一个 WKT（Well Known Text）转化为对应的内存的几何形式
别名
- ST_GEOMFROMTEXT
语法
ST_GEOMETRYFROMTEXT( <wkt>)
参数
| 参数 | 说明 |
|---|---|
<wkt> | 图形的内存形式 |
支持的WKT格式:
POINT- 空间中的单个点LINESTRING- 连接的线段序列POLYGON- 由一个或多个环定义的封闭区域, 要求至少有三个不同的点且首尾闭合MULTIPOLYGON- 多边形的集合, 要求多边形之间仅能存在有限个离散点的接触
备注
从 Apache Doris 3.0.6 开始支持 MULTIPOLYGON 格式解析
返回值
WKB 的对应的几何存储形式
当输入的 WKT 格式不符合规范或输入为 NULL 时返回 NULL。
举例
-- POINT 样例
SELECT ST_AsText(ST_GeometryFromText("POINT (1 1)"));
+-----------------------------------------------+
| ST_AsText(ST_GeometryFromText("POINT (1 1)")) |
+-----------------------------------------------+
| POINT (1 1) |
+-----------------------------------------------+
-- POINT 不合法样例(端点过多)
SELECT ST_AsText(ST_GeometryFromText("POINT (1 1, 2 2)"));
+----------------------------------------------------+
| ST_AsText(ST_GeometryFromText("POINT (1 1, 2 2)")) |
+----------------------------------------------------+
| NULL |
+----------------------------------------------------+
-- LINESTRING 样例
SELECT ST_AsText(ST_GeometryFromText("LINESTRING (1 1, 2 2)"));
+---------------------------------------------------------+
| st_astext(st_geometryfromtext('LINESTRING (1 1, 2 2)')) |
+---------------------------------------------------------+
| LINESTRING (1 1, 2 2) |
+---------------------------------------------------------+
-- LINESTRING 不合法样例(端点过少)
SELECT ST_AsText(ST_GeometryFromText("LINESTRING (1 1)"));
+----------------------------------------------------+
| ST_AsText(ST_GeometryFromText("LINESTRING (1 1)")) |
+----------------------------------------------------+
| NULL |
+----------------------------------------------------+
-- POLYGON 样例
SELECT ST_AsText(ST_GeometryFromText("POLYGON ((0 0, 1 0, 1 1, 0 1, 0 0))"));
+-----------------------------------------------------------------------+
| ST_AsText(ST_GeometryFromText("POLYGON ((0 0, 1 0, 1 1, 0 1, 0 0))")) |
+-----------------------------------------------------------------------+
| POLYGON ((0 0, 1 0, 1 1, 0 1, 0 0)) |
+-----------------------------------------------------------------------+
-- POLYGON 不合法样例(首尾不闭合)
SELECT ST_AsText(ST_GeometryFromText("POLYGON ((0 0, 1 0, 1 1, 0 1))"));
+------------------------------------------------------------------+
| ST_AsText(ST_GeometryFromText("POLYGON ((0 0, 1 0, 1 1, 0 1))")) |
+------------------------------------------------------------------+
| NULL |
+------------------------------------------------------------------+
-- POLYGON 不合法样例(端点过少)
SELECT ST_AsText(ST_GeometryFromText("POLYGON ((0 0, 1 0, 0 0))"));
+-------------------------------------------------------------+
| ST_AsText(ST_GeometryFromText("POLYGON ((0 0, 1 0, 0 0))")) |
+-------------------------------------------------------------+
| NULL |
+-------------------------------------------------------------+
-- MULTIPOLYGON 样例
SELECT ST_AsText(ST_GeometryFromText("MULTIPOLYGON (((0 0, 1 0, 1 1, 0 1, 0 0)), ((2 2, 3 2, 3 3, 2 3, 2 2)))"));
+-----------------------------------------------------------------------------------------------------------+
| ST_AsText(ST_GeometryFromText("MULTIPOLYGON (((0 0, 1 0, 1 1, 0 1, 0 0)), ((2 2, 3 2, 3 3, 2 3, 2 2)))")) |
+-----------------------------------------------------------------------------------------------------------+
| MULTIPOLYGON (((0 0, 1 0, 1 1, 0 1, 0 0)), ((2 2, 3 2, 3 3, 2 3, 2 2))) |
+-----------------------------------------------------------------------------------------------------------+
-- MULTIPOLYGON 样例(仅有有限个离散点接触)
SELECT ST_AsText(ST_GeometryFromText("MULTIPOLYGON (((0 0, 10 0, 10 10, 0 10, 0 0), (4 4, 6 4, 6 6, 4 6, 4 4)), ((4 5, 5 4, 6 5, 5 6, 4 5)))"));
+------------------------------------------------------------------------------------------------------------------------------------------+
| ST_AsText(ST_GeometryFromText("MULTIPOLYGON (((0 0, 10 0, 10 10, 0 10, 0 0), (4 4, 6 4, 6 6, 4 6, 4 4)), ((4 5, 5 4, 6 5, 5 6, 4 5)))")) |
+------------------------------------------------------------------------------------------------------------------------------------------+
| MULTIPOLYGON (((0 0, 10 0, 10 10, 0 10, 0 0), (4 4, 6 4, 6 6, 4 6, 4 4)), ((4 5, 5 4, 6 5, 5 6, 4 5))) |
+------------------------------------------------------------------------------------------------------------------------------------------+
-- MULTIPOLYGON 不合法样例(存在重叠部分)
SELECT ST_AsText(ST_GeometryFromText("MULTIPOLYGON (((0 0, 10 0, 10 10, 0 10, 0 0)), ((10 0, 20 0, 20 10, 10 10, 10 0)))"));
+----------------------------------------------------------------------------------------------------------------------+
| ST_AsText(ST_GeometryFromText("MULTIPOLYGON (((0 0, 10 0, 10 10, 0 10, 0 0)), ((10 0, 20 0, 20 10, 10 10, 10 0)))")) |
+----------------------------------------------------------------------------------------------------------------------+
| NULL |
+----------------------------------------------------------------------------------------------------------------------+
-- 输入 NULL
SELECT ST_AsText(ST_GeometryFromText(NULL));
+--------------------------------------+
| ST_AsText(ST_GeometryFromText(NULL)) |
+--------------------------------------+
| NULL |
+--------------------------------------+
