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ST_Aggr_Union

Definition

Die Funktion "ST_Aggr_Union" gibt eine einzelne Geometrie zurück, die die Vereinigungsmenge aller Eingabegeometrien ist.

Syntax

Oracle

sde.st_aggr_union(geometry sde.st_geometry)

SQLite

st_aggr_union(geometry geometryblob)

Rückgabetyp

Oracle

ST_Geometry

SQLite

Geometryblob

Beispiel

Ein Marketingfachmann muss eine Geometrie aller Einzugsgebiete erstellen, in denen der Absatz 1000 Einheiten übersteigt. Für dieses Beispiel erstellen Sie die Tabelle "service_territories1" und füllen Sie mit Absatzzahlen. Anschließend verwenden Sie "st_aggr_union" in einer SELECT-Anweisung, um das Multipolygon zurückzugeben, das die Vereinigungsmenge aller Geometrien darstellt, in denen der Absatz größer gleich 1000 Einheiten war.

Oracle

--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)))

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