Voyons comment utiliser l'extension PostGIS de PostgreSQL pour stocker et gérer de l'information géographique dans un SGBD.
CREATE TABLE my4capitals (id serial PRIMARY KEY, name text); SELECT AddGeometryColumn( 'my4capitals', 'the_geom', 4326, 'POINT', 2 );
INSERT INTO my4capitals VALUES ( nextval('my4capitals_id_seq'), 'Paris', ST_GeometryFromText( 'POINT(2.333 48.867)', 4326)); INSERT INTO my4capitals VALUES ( nextval('my4capitals_id_seq'), 'Bern', ST_GeometryFromText( 'POINT(7.433 46.95)', 4326)); INSERT INTO my4capitals VALUES ( nextval('my4capitals_id_seq'), 'Rome', ST_GeometryFromText( 'POINT(12.5 41.883)', 4326)); INSERT INTO my4capitals VALUES ( nextval('my4capitals_id_seq'), 'Madrid', ST_GeometryFromText( 'POINT(-3.71 40.41)', 4326));
SELECT ST_AsEWKT(the_geom) FROM my4capitals; SELECT ST_AsText(the_geom) FROM my4capitals; SELECT ST_AsGeoJSON(the_geom) FROM my4capitals;
SELECT ST_AsEWKT(ST_Transform(the_geom, 21781)), ST_AsEWKT(the_geom) FROM my4capitals;