Geometry SQL的访问函数ST_IsRing_云数据库 RDS(RDS)-阿里云帮助中心

当输入Geometry对象在判定条件ST_IsClosed下为true且ST_IsSimple也为true时，返回true。

语法

boolean  ST_IsRing(geometry  g);

参数

参数名称	描述
g	目标Geometry对象。

示例

返回true的情况：

SELECT ST_IsRing(geom), ST_IsClosed(geom), ST_IsSimple(geom) FROM (SELECT 'LINESTRING(0 0,0 2,2 0,0 0)'::geometry AS geom) AS test;
 st_isring | st_isclosed | st_issimple
-----------+-------------+-------------
 t         | t           | t
(1 row)

返回false的情况：

SELECT ST_IsRing(geom), ST_IsClosed(geom), ST_IsSimple(geom) FROM (SELECT 'LINESTRING(0 0,0 2,0 0)'::geometry AS geom) AS test;
 st_isring | st_isclosed | st_issimple
-----------+-------------+-------------
 f         | t           | f
(1 row)