ST_Boundary

定义

ST_Boundary 获取一个几何对象，然后以几何对象形式返回其组合边界。

语法

`sde.st_boundary (g1 sde.st_geometry)`

ST_Geometry

示例

Oracle

``````CREATE TABLE boundaries (geotype varchar(20), geometry sde.st_geometry);

INSERT INTO BOUNDARIES VALUES (
'Point',
sde.st_pointfromtext ('point (10.02 20.01)', 0)
);

INSERT INTO BOUNDARIES VALUES (
'Linestring',
sde.st_linefromtext ('linestring (10.02 20.01, 10.32 23.98, 11.92 25.64)', 0)
);

INSERT INTO BOUNDARIES VALUES (
'Polygon',
sde.st_polyfromtext ('polygon ((10.02 20.01, 11.92 35.64, 25.02 34.15, 19.15 33.94, 10.02 20.01))', 0)
);

INSERT INTO BOUNDARIES VALUES (
'Multipoint',
sde.st_mpointfromtext ('multipoint (10.02 20.01, 10.32 23.98, 11.92 25.64)', 0)
);

INSERT INTO BOUNDARIES VALUES (
'Multilinestring',
sde.st_mlinefromtext ('multilinestring ((10.02 20.01, 10.32 23.98, 11.92 25.64), (9.55 23.75, 15.36 30.11))', 0)
);

INSERT INTO BOUNDARIES VALUES (
'Multipolygon',
sde.st_mpolyfromtext ('multipolygon (((10.02 20.01, 11.92 35.64, 25.02 34.15, 19.15 33.94, 10.02 20.01), (51.71 21.73,73.36 27.04,71.52 32.87, 52.43 31.90, 51.71 21.73)))', 0)
);

SELECT type, sde.st_astext (sde.st_boundary (geometry)) "The boundary"
FROM BOUNDARIES;

GEOTYPE            The boundary

Point              POINT EMPTY
Linestring         MULTIPOINT(10.02000000 20.01000000, 11.92000000 25.64000000)
Polygon            MULTILINESTRING ((10.02000000 20.01000000, 19.15000000 33.94000000,25.02000000 34.15000000, 11.92000000 35.64000000, 10.02000000 20.01000000))
Multipoint         POINT EMPTY
Multilinestring    MULTIPOINT (9.55000000 23.75000000, 10.02000000 20.01000000, 11.92000000 25.64000000, 15.36000000 30.11000000)
Multipolygon       MULTILINESTRING((51.71000000 21.73000000, 73.36000000 27.04000000, 71.52000000 32.87000000, 52.43000000 31.90000000, 51.71000000 21.73000000), (10.02000000 20.01000000, 19.15000000 33.94000000, 25.02000000 34.15000000, 11.92000000 35.64000000, 10.02000000 20.01000000))
``````

PostgreSQL

``````CREATE TABLE boundaries (type varchar(20), geometry st_geometry);

INSERT INTO boundaries VALUES (
'Point',
st_point ('point (10.02 20.01)', 0)
);

INSERT INTO boundaries VALUES (
'Linestring',
st_linestring ('linestring (10.02 20.01, 10.32 23.98, 11.92 25.64)', 0)
);

INSERT INTO boundaries VALUES (
'Polygon',
st_polygon ('polygon ((10.02 20.01, 11.92 35.64, 25.02 34.15, 19.15 33.94, 10.02 20.01))', 0)
);

INSERT INTO boundaries VALUES (
'Multipoint',
st_multipoint ('multipoint (10.02 20.01, 10.32 23.98, 11.92 25.64)', 0)
);

INSERT INTO boundaries VALUES (
'Multilinestring',
st_multilinestring ('multilinestring ((10.02 20.01, 10.32 23.98, 11.92 25.64),
(9.55 23.75, 15.36 30.11))', 0)
);

INSERT INTO boundaries VALUES (
'Multipolygon',
st_multipolygon ('multipolygon (((10.02 20.01, 11.92 35.64, 25.02 34.15, 19.15 33.94, 10.02 20.01),
(51.71 21.73, 73.36 27.04, 71.52 32.87, 52.43 31.90, 51.71 21.73)))', 0)
);

SELECT type, st_astext (st_boundary (geometry))
AS "The boundary"
FROM boundaries;

type              The boundary

Point              EMPTY
Linestring         MULTIPOINT(10.02000000 20.01000000, 11.92000000
25.64000000)
Polygon            LINESTRING ((10.02000000 20.01000000, 19.15000000
33.94000000,25.02000000 34.15000000, 11.92000000 35.64000000, 10.02000000
20.01000000))
Multipoint         EMPTY
Multilinestring    MULTIPOINT (9.55000000 23.75000000, 10.02000000
20.01000000, 11.92000000 25.64000000, 15.36000000 30.11000000)
Multipolygon       MULTILINESTRING((51.71000000 21.73000000, 73.36000000
27.04000000, 71.52000000 32.87000000, 52.43000000 31.90000000,
51.71000000 21.73000000), (10.02000000 20.01000000, 19.15000000
33.94000000, 25.02000000 34.15000000, 11.92000000 35.64000000,
10.02000000 20.01000000))
``````
9/15/2013