ST_Aggr_ConvexHull

メモ:

Oracle と SQLite のみ

定義

ST_Aggr_ConvexHull は、すべての入力ジオメトリのユニオンから得られる凸包のジオメトリを 1 つ作成します。実際には、ST_Aggr_ConvexHull は ST_ConvexHull (ST_Aggr_Union (ジオメトリ)) に相当します。

構文

Oracle

sde.st_aggr_convexhull (geometry sde.st_geometry)

SQLite

st_aggr_convexhull (geometry st_geometry)

戻り値のタイプ

Oracle

ST_Geometry

SQLite

Geometryblob

例

この例では、service_territories テーブルを作成し、すべてのジオメトリを集約する SELECT ステートメントを実行して、すべてのシェープのユニオンから得られる凸包を表す単一のジオメトリが生成されます。

Oracle

CREATE TABLE service_territories 
 (ID integer not null, UNITS number, SHAPE sde.st_geometry);

INSERT INTO service_territories (id, units, shape) VALUES (
 1, 
 1250, 
 sde.st_polygon ('polygon ((20 30, 30 30, 30 40, 20 40, 20 30))', 4326)
);
 
INSERT INTO service_territories (id, units, shape) VALUES (
 2, 
 875, 
 sde.st_polygon ('polygon ((30 30, 30 50, 50 50, 50 30, 30 30))', 4326)
);
 
INSERT INTO service_territories (id, units, shape) VALUES (
 3, 
 1700, 
 sde.st_polygon ('polygon ((40 40, 40 60, 60 60, 60 40, 40 40))', 4326)
);

SELECT sde.st_astext(sde.st_aggr_convexhull(shape)) CONVEX_HULL
 FROM service_territories 
 WHERE units >= 1000;

CONVEX_HULL

POLYGON  (( 20.00000000 40.00000000, 20.00000000 30.00000000, 30.00000000 30.00000000, 
60.00000000 40.00000000, 60.00000000 60.00000000, 40.00000000 60.00000000, 20.00000000 40.00000000))

SQLite

CREATE TABLE service_territories (
  ID integer primary key autoincrement not null, 
  UNITS numeric
);

SELECT AddGeometryColumn(
 NULL,
 'service_territories',
 'shape',
 4326,
 'polygon',
 'xy',
 'null'
);

INSERT INTO service_territories (units, shape) VALUES (
 1250, 
 st_polygon ('polygon ((20 30, 30 30, 30 40, 20 40, 20 30))', 4326)
);
 
INSERT INTO service_territories (units, shape) VALUES (
 875, 
 st_polygon ('polygon ((30 30, 30 50, 50 50, 50 30, 30 30))', 4326)
);
 
INSERT INTO service_territories (units, shape) VALUES (
 1700, 
 st_polygon ('polygon ((40 40, 40 60, 60 60, 60 40, 40 40))', 4326)
);

SELECT st_astext(st_aggr_convexhull(shape)) AS "CONVEX HULL"
 FROM service_territories 
 WHERE units >= 1000;

CONVEX HULL

POLYGON  (( 20.00000000 40.00000000, 20.00000000 30.00000000, 30.00000000 30.00000000, 
60.00000000 40.00000000, 60.00000000 60.00000000, 40.00000000 60.00000000, 20.00000000 40.00000000))