ST_Distance
Definición
ST_Distance devuelve la distancia entre dos geometrías. La distancia se mide desde el vértice más cercano de las dos geometrías.
Sintaxis
Oracle y PostgreSQL
sde.st_distance (geometry1 sde.st_geometry, geometry2 sde.st_geometry)
SQLite
st_distance (geometry1 geometryblob, geometry2 geometryblob)
st_distance (geometry1 geometryblob, geometry2 geometryblob, unit_name text)
Los nombres de unidad válidos son los siguientes:
Milímetro | Pulgada | Yarda | Vínculo |
Centímetro | Inch_US | Yard_US | Link_US |
Decímetro | Pie | Yard_Clarke | Link_Clarke |
Metro | Foot_US | Yard_Sears | Link_Sears |
Meter_German | Foot_Clarke | Yard_Sears_1922_Truncated | Link_Sears_1922_Truncated |
Kilómetro | Foot_Sears | Yard_Benoit_1895_A | Link_Benoit_1895_B |
50_Kilometers | Foot_Sears_1922_Truncated | Yard_Indian | Cadena |
150_Kilometers | Foot_Benoit_1895_A | Yard_Indian_1937 | Chain_US |
Vara_US | Foot_1865 | Yard_Indian_1962 | Chain_Clarke |
Smoot | Foot_Indian | Yard_Indian_1975 | Chain_Sears |
Foot_Indian_1937 | Fathom | Chain_Sears_1922_Truncated | |
Foot_Indian_1962 | Mile_US | Chain_Benoit_1895_A | |
Foot_Indian_1975 | Statute_Mile | Rod | |
Foot_Gold_Coast | Nautical_Mile | Rod_US | |
Foot_British_1936 | Nautical_Mile_US | ||
Nautical_Mile_UK |
Tipo de devolución
Precisión doble
Ejemplo
Se crean y se completan dos tablas, study1 y zones. A continuación, la función ST_Distance se usa para determinar la distancia entre el límite de cada subárea y los polígonos de la tabla de área study1 que tienen el código de uso 400. Puesto que hay tres zonas con esta forma, se deben devolver tres registros.
En Oracle y PostgreSQL, las unidades se definen en el sistema de proyección que se está utilizando. En estos ejemplos, se usan grados decimales. En SQLite, puede especificar las unidades. En el ejemplo de SQLite, se especifica el kilómetro; por tanto, la distancia se devuelve en kilómetros.
Oracle
--Create tables and insert values.
CREATE TABLE zones (
sa_id integer,
usecode integer,
shape sde.st_geometry
);
CREATE TABLE study1 (
code integer unique,
shape sde.st_geometry
);
INSERT INTO zones (sa_id, usecode, shape) VALUES (
1,
400,
sde.st_polygon ('polygon ((0 0, 0 10, 10 10, 10 0, 0 0))', 4326)
);
INSERT INTO zones (sa_id, usecode, shape) VALUES (
2,
400,
sde.st_polygon ('polygon ((12 3, 12 6, 15 6, 15 3, 12 3))', 4326)
);
INSERT INTO zones (sa_id, usecode, shape) VALUES (
3,
400,
sde.st_polygon ('polygon ((20 0, 20 10, 30 10, 30 0, 20 0))', 4326)
);
INSERT INTO zones (sa_id, usecode, shape) VALUES (
4,
402,
sde.st_polygon ('polygon ((40 0, 40 10, 50 10, 50 0, 40 0))', 4326)
);
INSERT INTO study1 (code, shape) VALUES (
400,
sde.st_polygon ('polygon ((-1 -1, -1 11, 11 11, 19 11, 31 11, 31 -1, 19 -1, 11 -1, -1 -1))', 4326)
);
INSERT INTO study1 (code, shape) VALUES (
402,
sde.st_polygon ('polygon ((39 -1, 39 11, 51 11, 51 -1, 39 -1))', 4326)
);
SELECT UNIQUE s.code, z.sa_id, sde.st_distance(z.shape, sde.st_boundary(s.shape)) DISTANCE
FROM zones z, study1 s
WHERE z.usecode = s.code AND s.code = 400
ORDER BY DISTANCE;
code sa_id DISTANCE
400 1 1
400 3 1
400 3 4
PostgreSQL
--Create tables and insert values.
CREATE TABLE zones (
sa_id integer,
usecode integer,
shape sde.st_geometry
);
CREATE TABLE study1 (
code integer unique,
shape sde.st_geometry
);
INSERT INTO zones (sa_id, usecode, shape) VALUES (
1,
400,
sde.st_polygon ('polygon ((0 0, 0 10, 10 10, 10 0, 0 0))', 4326)
);
INSERT INTO zones (sa_id, usecode, shape) VALUES (
2,
400,
sde.st_polygon ('polygon ((12 3, 12 6, 15 6, 15 3, 12 3))', 4326)
);
INSERT INTO zones (sa_id, usecode, shape) VALUES (
3,
400,
sde.st_polygon ('polygon ((20 0, 20 10, 30 10, 30 0, 20 0))', 4326)
);
INSERT INTO zones (sa_id, usecode, shape) VALUES (
4,
402,
sde.st_polygon ('polygon ((40 0, 40 10, 50 10, 50 0, 40 0))', 4326)
);
INSERT INTO study1 (code, shape) VALUES (
400,
sde.st_polygon ('polygon ((-1 -1, -1 11, 11 11, 19 11, 31 11, 31 -1, 19 -1, 11 -1, -1 -1))', 4326)
);
INSERT INTO study1 (code, shape) VALUES (
402,
sde.st_polygon ('polygon ((39 -1, 39 11, 51 11, 51 -1, 39 -1))', 4326)
);
--
SELECT DISTINCT s.code, z.sa_id, sde.st_distance(z.shape, sde.st_boundary(s.shape))
AS Distance
FROM zones z, study1 s
WHERE z.usecode = s.code AND s.code = 400
ORDER BY Distance;
code sa_id distance
400 1 1
400 3 1
400 2 4
SQLite
--Create tables, add geometry columns, and insert values.
CREATE TABLE zones (
sa_id integer primary key autoincrement not null,
usecode integer
);
SELECT AddGeometryColumn (
NULL,
'zones',
'shape',
4326,
'polygon',
'xy',
'null'
);
CREATE TABLE study1 (
code integer unique
);
SELECT AddGeometryColumn (
NULL,
'study1',
'shape',
4326,
'polygon',
'xy',
'null'
);
INSERT INTO zones (usecode, shape) VALUES (
400,
st_polygon ('polygon ((0 0, 0 10, 10 10, 10 0, 0 0))', 4326)
);
INSERT INTO zones (usecode, shape) VALUES (
400,
st_polygon ('polygon ((12 3, 12 6, 15 6, 15 3, 12 3))', 4326)
);
INSERT INTO zones (usecode, shape) VALUES (
400,
st_polygon ('polygon ((20 0, 20 10, 30 10, 30 0, 20 0))', 4326)
);
INSERT INTO zones (usecode, shape) VALUES (
402,
st_polygon ('polygon ((40 0, 40 10, 50 10, 50 0, 40 0))', 4326)
);
INSERT INTO study1 (code, shape) VALUES (
400,
st_polygon ('polygon ((-1 -1, -1 11, 11 11, 19 11, 31 11, 31 -1, 19 -1, 11 -1, -1 -1))', 4326)
);
INSERT INTO study1 (code, shape) VALUES (
402,
st_polygon ('polygon ((39 -1, 39 11, 51 11, 51 -1, 39 -1))', 4326)
);
SELECT DISTINCT s.code, z.sa_id, st_distance(z.shape, st_boundary(s.shape), "kilometer")
AS "Distance(km)"
FROM zones z, study1 s
WHERE z.usecode = s.code AND s.code = 400
ORDER BY "Distance(km)";
code sa_id Distance(km)
400 1 109.63919620267
400 3 109.63919620267
400 2 442.30025845408