Todos estos atributos pueden probarse y, si es necesario, usarse como Predicciones espaciales. Las predicciones espaciales se aplican como funciones de los miembros que regresan 0
(falso) o 1
(cierto).
SELECT 'isClosed' AS "Feature", NEW ST_CircularString('CircularString (0 0, 3 4, 0 4, -3 4, 0 0)').ST_isClosed() AS "FeatureTest" FROM "DUMMY"
union all
SELECT 'isSimple' AS "Feature", NEW ST_CircularString('CircularString (0 0, 3 4, 0 4, -3 4, 0 0)').ST_isSimple() AS "FeatureTest" FROM "DUMMY"
union all
SELECT 'isRing' AS "Feature", NEW ST_CircularString('CircularString (0 0, 3 4, 0 4, -3 4, 0 0)').ST_isRing() AS "FeatureTest" FROM "DUMMY";
Ahora realice la misma prueba en otra geometría, definida por ST_LineString('LINESTRING(0 0, 1 1, 0 1, 1 0)')
SELECT 'isClosed' AS "Feature", NEW ST_LineString('LINESTRING(0 0, 1 1, 0 1, 1 0)').ST_isClosed() AS "FeatureTest" FROM "DUMMY"
union all
SELECT 'isSimple' AS "Feature", NEW ST_LineString('LINESTRING(0 0, 1 1, 0 1, 1 0)').ST_isSimple() AS "FeatureTest" FROM "DUMMY"
union all
SELECT 'isRing' AS "Feature", NEW ST_LineString('LINESTRING(0 0, 1 1, 0 1, 1 0)').ST_isRing() AS "FeatureTest" FROM "DUMMY";