ST_GeometryN
定义
ST_GeometryN 获取一个集合和一个整数索引,然后返回集合中的第 n 个 ST_Geometry 对象。
语法
sde.st_geometryn (mpt1 sde.st_multipoint, index integer) sde.st_geometryn (mln1 sde.st_multilinestring, index integer) sde.st_geometryn (mpl1 sde.st_multipolygon, index integer)
返回类型
ST_Geometry
示例
在本示例中,将创建一个多面。然后使用 ST_GeometryN 列出多面的第二个元素。
Oracle
CREATE TABLE districts (dist_id integer, shape sde.st_multipolygon);
INSERT INTO DISTRICTS (dist_id, shape) VALUES (
1,
sde.st_multipolygon ('multipolygon (((-1 -1, -1 11, 11 11, 11 -1, -1 -1),
(19 -1, 19 11, 29 9, 31 -1, 19 -1), (39 -1, 39 11, 51 11, 51 -1, 39 -1)))', 0)
);
SELECT sde.st_astext (sde.st_geometryn (shape, 2)) Second_Element
FROM DISTRICTS;
Second_Element
POLYGON ((-1.00000000 -1.00000000, 11.00000000 -1.00000000, 11.0000000 0 11.000
PostgreSQL
CREATE TABLE districts (dist_id integer, shape sde.st_geometry);
INSERT INTO districts (dist_id, shape) VALUES (
1,
sde.st_multipolygon ('multipolygon (((-1 -1, -1 11, 11 11, 11 -1, -1 -1),
(19 -1, 19 11, 29 9, 31 -1, 19 -1), (39 -1, 39 11, 51 11, 51 -1, 39 -1)))', 0)
);
SELECT st_astext (sde.st_geometryn (shape, 2)) AS Second_Element
FROM districts;
Second_Element
POLYGON ((39 -1, 51 -1, 51 11, 39 11, 39 -1))
9/15/2013