ST_Buffer takes a geometry object and distance and returns a geometry object that is the buffer surrounding the source object.
Oracle
sde.st_buffer (g1 sde.st_geometry, distance double_precision)
PostgreSQL
st_buffer (g1 st_geometry, distance double_precision)
This example creates two tables, sensitive_areas and hazardous_sites; populates the tables; uses ST_Buffer to generate a buffer around the polygons in the hazardous_sites table; and finds where these buffers overlap the sensitive_areas polygons.
Oracle
CREATE TABLE sensitive_areas (id integer,
zone sde.st_geometry);
CREATE TABLE hazardous_sites (site_id integer,
name varchar(40),
location sde.st_geometry);
INSERT INTO sensitive_areas VALUES (
1,
sde.st_polygon ('polygon ((20 30, 30 30, 30 40, 20 40, 20 30))', 0)
);
INSERT INTO sensitive_areas VALUES (
2,
sde.st_polygon ('polygon ((30 30, 30 50, 50 50, 50 30, 30 30))', 0)
);
INSERT INTO sensitive_areas VALUES (
3,
sde.st_polygon ('polygon ((40 40, 40 60, 60 60, 60 40, 40 40))', 0)
);
INSERT INTO hazardous_sites VALUES (
102,
'W. H. KleenareChemical Repository',
sde.st_pointfromtext ('point (60 60)', 0)
);
SELECT sa.id "Sensitive Areas", hs.name "Hazardous Sites"
FROM sensitive_areas sa, hazardous_sites hs
WHERE sde.st_overlaps (sa.zone, sde.st_buffer (hs.location, .01)) = 1;
PostgreSQL
CREATE TABLE sensitive_areas (id integer,
zone st_geometry);
CREATE TABLE hazardous_sites (site_id integer,
name varchar(40),
location st_geometry);
INSERT INTO sensitive_areas VALUES (
1,
st_polygon ('polygon ((20 30, 30 30, 30 40, 20 40, 20 30))', 0)
);
INSERT INTO sensitive_areas VALUES (
2,
st_polygon ('polygon ((30 30, 30 50, 50 50, 50 30, 30 30))', 0)
);
INSERT INTO sensitive_areas VALUES (
3,
st_polygon ('polygon ((40 40, 40 60, 60 60, 60 40, 40 40))', 0)
);
INSERT INTO hazardous_sites VALUES (
102,
'W. H. KleenareChemical Repository',
st_point ('point (60 60)', 0)
);
SELECT sa.id AS "Sensitive Areas", hs.name AS "Hazardous Sites"
FROM sensitive_areas sa, hazardous_sites hs
WHERE st_overlaps (sa.zone, st_buffer (hs.location, .01)) = 't';
Sensitive Areas Hazardous Sites
3 W.H. KleenareChemical Repository