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ST_Intersects

Definition

ST_Intersects returns 1 (Oracle and SQLite) or t (PostgreSQL) if the intersection of two geometries doesn't result in an empty set; otherwise, it returns 0 (Oracle and SQLite) or f (PostgreSQL).

Syntax

Oracle and PostgreSQL

sde.st_intersects (geometry1 sde.st_geometry, geometry2 sde.st_geometry)

SQLite

st_intersects (geometry1 geometryblob, geometry2 geometryblob)

Return type

Boolean

Example

The fire marshal wants a list of sensitive areas within a radius of a hazardous waste site.

The sensitive areas are stored in the sensitive_areas table. The shape column, defined as a polygon, stores the outline of each of the sensitive areas.

The hazardous sites are stored in the hazardous_sites table. The site column, defined as a point, stores a location that is the geographic center of each hazardous site.

The SELECT query creates a buffer radius around each hazardous site and returns a list of sensitive areas that intersect the hazardous sites buffers.

Oracle

--Create and populate tables.
CREATE TABLE sensitive_areas (
 id integer,
 shape sde.st_geometry
); 

CREATE TABLE hazardous_sites (
 id integer,
 site sde.st_geometry
);

INSERT INTO sensitive_areas VALUES (
 1,
 sde.st_geometry ('polygon ((20 30, 30 30, 30 40, 20 40, 20 30))', 4326)
);

INSERT INTO sensitive_areas VALUES (
 2,
 sde.st_geometry ('polygon ((30 30, 30 50, 50 50, 50 30, 30 30))', 4326)
);

INSERT INTO sensitive_areas VALUES (
 3,
 sde.st_geometry ('polygon ((40 40, 40 60, 60 60, 60 40, 40 40))', 4326)
);

INSERT INTO hazardous_sites VALUES (
 4,
 sde.st_geometry ('point (60 60)', 4326)
);

INSERT INTO hazardous_sites VALUES (
 5,
 sde.st_geometry ('point (30 30)', 4326)
);

--Create a buffer around the hazardous sites, then find the hazardous site buffers that intersect sensitive areas.
SELECT sa.id SA_ID, hs.id HS_ID
 FROM SENSITIVE_AREAS sa, HAZARDOUS_SITES hs
 WHERE sde.st_intersects (sde.st_buffer (hs.site, .1), sa.shape) = 1
 ORDER BY sa.id;

SA_ID      HS_ID

    1          5
    2          5
    3          4

PostgreSQL

--Create and populate tables.
CREATE TABLE sensitive_areas (
 id serial,
 shape sde.st_geometry
); 

CREATE TABLE hazardous_sites (
 id serial,
 site sde.st_geometry
);

INSERT INTO sensitive_areas (shape) VALUES (
 sde.st_geometry ('polygon ((20 30, 30 30, 30 40, 20 40, 20 30))', 4326)
);

INSERT INTO sensitive_areas (shape) VALUES (
 sde.st_geometry ('polygon ((30 30, 30 50, 50 50, 50 30, 30 30))', 4326)
);

INSERT INTO sensitive_areas (shape) VALUES (
 sde.st_geometry ('polygon ((40 40, 40 60, 60 60, 60 40, 40 40))', 4326)
);

INSERT INTO hazardous_sites (site) VALUES (
 sde.st_geometry ('point (60 60)', 4326)
);

INSERT INTO hazardous_sites (site) VALUES (
 sde.st_geometry ('point (30 30)', 4326)
);

--Create a buffer around the hazardous sites, then find the hazardous site buffers that intersect sensitive areas.
SELECT sa.id AS sid, hs.id AS hid
 FROM sensitive_areas sa, hazardous_sites hs
 WHERE sde.st_intersects (sde.st_buffer (hs.site, .1), sa.shape) = 't'
 ORDER BY sa.id;

sid     hid

  1       2
  2       2
  3       1

SQLite

--Create and populate tables.
CREATE TABLE sensitive_areas (
 id integer primary key autoincrement not null
); 

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

CREATE TABLE hazardous_sites (
 id integer primary key autoincrement not null
);

SELECT AddGeometryColumn (
 NULL,
 'hazardous_sites',
 'site',
 4326,
 'point',
 'xy',
 'null'
);

INSERT INTO sensitive_areas (shape) VALUES (
 st_geometry ('polygon ((20 30, 30 30, 30 40, 20 40, 20 30))', 4326)
);

INSERT INTO sensitive_areas (shape) VALUES (
 st_geometry ('polygon ((30 30, 30 50, 50 50, 50 30, 30 30))', 4326)
);

INSERT INTO sensitive_areas (shape) VALUES (
 st_geometry ('polygon ((40 40, 40 60, 60 60, 60 40, 40 40))', 4326)
);

INSERT INTO hazardous_sites (site) VALUES (
 st_geometry ('point (60 60)', 4326)
);

INSERT INTO hazardous_sites (site) VALUES (
 st_geometry ('point (30 30)', 4326)
);

--Create a buffer around the hazardous sites, then find the hazardous site buffers that intersect sensitive areas.
SELECT sa.id AS "sid", hs.id AS "hid"
 FROM sensitive_areas sa, hazardous_sites hs
 WHERE st_intersects (st_buffer (hs.site, .1), sa.shape) = 1
 ORDER BY sa.id;

sid     hid

  1       2
  2       2
  3       1

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