ST_Aggr_Union

定义

ST_Aggr_Union 返回表示所有输入几何的并集的单个几何。

请注意，从 10.5.1 版本开始支持在 PostgreSQL 中配合使用 ST_Aggr_Union 和 ST_Geometry。

语法

Oracle 和 PostgreSQL

sde.st_aggr_union(geometry sde.st_geometry)

SQLite

st_aggr_union(geometry geometryblob)

返回类型

Oracle 和 PostgreSQL

ST_Geometry

SQLite

Geometryblob

示例

市场分析师需要创建表示销售量超过 1,000 的所有服务区的单个几何。在本示例中，您将创建 service_territories1 表并使用销售值数量填充表。然后使用 SELECT 语句中的 st_aggr_union 返回表示销售量等于或大于 1,000 的所有几何的并集的多面。

Oracle 和 PosgreSQL

--Create and populate tables.
CREATE TABLE service_territories1 (
 ID integer not null,
 UNITS number,
 SHAPE sde.st_geometry);
INSERT INTO service_territories1 (id, units, shape) VALUES (
 1, 
 1250,
 sde.st_polygon ('polygon ((20 30, 30 30, 30 40, 20 40, 20 30))', 4326)
);
 
INSERT INTO service_territories1 (id, units, shape) VALUES (
 2, 
 875,
 sde.st_polygon ('polygon ((30 30, 30 50, 50 50, 50 30, 30 30))', 4326)
);
 
INSERT INTO service_territories1 (id, units, shape) VALUES (
 3, 
 1700,
 sde.st_polygon ('polygon ((40 40, 40 60, 60 60, 60 40, 40 40))', 4326)
);

--Union of all geometries for which sales numbers are >= 1,000 units.
SELECT sde.st_astext(sde.st_aggr_union(shape)) UNION_SHAPE
  FROM service_territories1 
  WHERE units >= 1000;
UNION_SHAPE
MULTIPOLYGON  ((( 20.00000000 30.00000000, 30.00000000 30.00000000, 30.00000000
40.00000000, 20.00000000 40.00000000, 20.00000000 30.00000000)),(( 40.00000000 40.00000000, 
60.00000000 40.00000000, 60.00000000 60.00000000, 40.00000000 60.00000000, 
40.00000000 40.00000000)))

SQLite

--Create table, add geometry column to it, and populate table.
CREATE TABLE service_territories1 (
 id integer primary key autoincrement not null, 
 units number
);
SELECT AddGeometryColumn(
 NULL,
 'service_territories1',
 'shape',
 4326,
 'polygon',
 'xy',
 'null'
);
INSERT INTO service_territories1 (units, shape) VALUES (
 1250,
 st_polygon ('polygon ((20 30, 30 30, 30 40, 20 40, 20 30))', 4326)
);
 
INSERT INTO service_territories1 (units, shape) VALUES (
 875,
 st_polygon ('polygon ((30 30, 30 50, 50 50, 50 30, 30 30))', 4326)
);
 
INSERT INTO service_territories1 (units, shape) VALUES (
 1700,
 st_polygon ('polygon ((40 40, 40 60, 60 60, 60 40, 40 40))', 4326)
);

--Union of all geometries for which sales numbers are >= 1,000 units.
SELECT st_astext(st_aggr_union(shape)) 
 AS "UNION_SHAPE"
 FROM service_territories1 
 WHERE units >= 1000;
UNION_SHAPE
MULTIPOLYGON ((( 40.00000000 40.00000000, 60.00000000 40.00000000, 60.00000000 6
0.00000000, 40.00000000 60.00000000, 40.00000000 40.00000000)),(( 20.00000000 30
.00000000, 30.00000000 30.00000000, 30.00000000 40.00000000, 20.00000000 40.0000
0000, 20.00000000 30.00000000)))