定义
ST_Dimension 用于返回几何对象的维度。在这种情况下，维度是指长度和宽度。例如，点既没有长度也没有宽度，所以其维度为 0；而线只有长度却没有宽度，因此其维度为 1。
语法
Oracle 和 PostgreSQL
sde.st_dimension (geometry1 sde.st_geometry)
SQLite
st_dimension (geometry1 geometryblob)
返回类型
整型
示例
创建包含 geotype 和 g1 两列的 dimension_test 表。geotype 列存储的是 g1 几何列中所存储的子类的名称。
SELECT 语句列出了 geotype 列中所存储的子类名称以及相应几何类型的维度。
Oracle
CREATE TABLE dimension_test (
geotype varchar(20),
g1 sde.st_geometry
);
INSERT INTO DIMENSION_TEST VALUES (
'Point',
sde.st_pointfromtext ('point (10.02 20.01)', 4326)
);
INSERT INTO DIMENSION_TEST VALUES (
'Linestring',
sde.st_linefromtext ('linestring (10.02 20.01, 10.32 23.98, 11.92 25.64)', 4326)
);
INSERT INTO DIMENSION_TEST 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 DIMENSION_TEST VALUES (
'Multipoint',
sde.st_mpointfromtext ('multipoint (10.02 20.01, 10.32 23.98, 11.92 25.64)', 4326)
);
INSERT INTO DIMENSION_TEST 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))', 4326)
);
INSERT INTO DIMENSION_TEST 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_dimension (g1) Dimension
FROM DIMENSION_TEST;
GEOTYPE Dimension
Point 0
Linestring 1
Polygon 2
Multipoint 0
Multilinestring 1
Multipolygon 2
PostgreSQL
CREATE TABLE dimension_test (
geotype varchar(20),
g1 sde.st_geometry
);
INSERT INTO dimension_test VALUES (
'Point',
sde.st_point ('point (10.02 20.01)', 4326)
);
INSERT INTO dimension_test VALUES (
'Linestring',
sde.st_linestring ('linestring (10.02 20.01, 10.32 23.98, 11.92 25.64)', 4326)
);
INSERT INTO dimension_test VALUES (
'Polygon',
sde.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 dimension_test VALUES (
'Multipoint',
sde.st_multipoint ('multipoint (10.02 20.01, 10.32 23.98, 11.92 25.64)', 4326)
);
INSERT INTO dimension_test VALUES (
'Multilinestring',
sde.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 dimension_test VALUES (
'Multipolygon',
sde.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, sde.st_dimension (g1)
AS Dimension
FROM dimension_test;
geotype dimension
Point 0
Linestring 1
Polygon 2
Multipoint 0
Multilinestring 1
Multipolygon 2
SQLite
CREATE TABLE dimension_test (
geotype varchar(20)
);
SELECT AddGeometryColumn (
NULL,
'dimension_test',
'g1',
4326,
'geometry',
'xy',
'null'
);
INSERT INTO dimension_test VALUES (
'Point',
st_point ('point (10.02 20.01)', 4326)
);
INSERT INTO dimension_test VALUES (
'Linestring',
st_linestring ('linestring (10.02 20.01, 10.32 23.98, 11.92 25.64)', 4326)
);
INSERT INTO dimension_test 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 dimension_test VALUES (
'Multipoint',
st_multipoint ('multipoint (10.02 20.01, 10.32 23.98, 11.92 25.64)', 4326)
);
INSERT INTO dimension_test 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 dimension_test 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_dimension (g1)
AS "Dimension"
FROM dimension_test;
geotype Dimension
Point 0
Linestring 1
Polygon 2
Multipoint 0
Multilines 1
Multipolyg 2