定义
ST_Boundary 获取一个几何，然后以几何对象形式返回其组合边界。
语法
Oracle 和 PostgreSQL
sde.st_boundary (geometry sde.st_geometry)
SQLite
st_boundary (geometry geometryblob)
返回类型
Oracle 和 PostgreSQL
ST_Geometry
SQLite
Geometryblob
示例
在本示例中，创建包含两列的 boundaries 表：type 和 geometry。后续的 INSERT 语句将为每个子类几何添加一条记录。ST_Boundary 函数检索存储在 geometry 列中的每个子类的边界。请注意，生成几何的维度始终小于输入几何的维度。点和多点始终生成表示空几何的边界，维度为 –1。线串和多线串返回多点边界，维度为 0。面或多面始终返回多线串边界，维度为 1。
Oracle
CREATE TABLE boundaries (
geotype varchar(20),
geometry sde.st_geometry
);
INSERT INTO BOUNDARIES VALUES (
'Point',
sde.st_pointfromtext ('point (10.02 20.01)', 4326)
);
INSERT INTO BOUNDARIES VALUES (
'Linestring',
sde.st_linefromtext ('linestring (10.02 20.01, 10.32 23.98, 11.92 25.64)', 4326)
);
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))', 4326)
);
INSERT INTO BOUNDARIES VALUES (
'Multipoint',
sde.st_mpointfromtext ('multipoint (10.02 20.01, 10.32 23.98, 11.92 25.64)', 4326)
);
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)))', 4326)
);
SELECT geotype, 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 (
geotype varchar(20),
geometry st_geometry
);
INSERT INTO boundaries VALUES (
'Point',
st_point ('point (10.02 20.01)', 4326)
);
INSERT INTO boundaries VALUES (
'Linestring',
st_linestring ('linestring (10.02 20.01, 10.32 23.98, 11.92 25.64)', 4326)
);
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))', 4326)
);
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))', 4326)
);
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)))', 4326)
);
SELECT geotype, st_astext (st_boundary (geometry))
AS "The boundary"
FROM boundaries;
geotype 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))
SQLite
CREATE TABLE boundaries (
geotype varchar(20)
);
SELECT AddGeometryColumn (
NULL,
'boundaries',
'geometry',
4326,
'geometry',
'xy',
'null'
);
INSERT INTO boundaries VALUES (
'Point',
st_point ('point (10.02 20.01)', 4326)
);
INSERT INTO boundaries VALUES (
'Linestring',
st_linestring ('linestring (10.02 20.01, 10.32 23.98, 11.92 25.64)', 4326)
);
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))', 4326)
);
INSERT INTO boundaries VALUES (
'Multipoint',
st_multipoint ('multipoint (10.02 20.01, 10.32 23.98, 11.92 25.64)', 4326)
);
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))', 4326)
);
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)))', 4326)
);
SELECT geotype, st_astext (st_boundary (geometry))
FROM boundaries;
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))