The SDO_GEOMETRY object type (described in SDO_GEOMETRY Object Type) has constructors that create a geometry object from a well-known text (WKT) string in CLOB or VARCHAR2 format, or from a well-known binary (WKB) object in BLOB format. The following constructor formats are available:
SDO_GEOMETRY(wkt CLOB, srid NUMBER DEFAULT NULL); SDO_GEOMETRY(wkt VARCHAR2, srid NUMBER DEFAULT NULL); SDO_GEOMETRY(wkb BLOB, srid NUMBER DEFAULT NULL);
If the created geometry is inserted into a table, the SRID value used with the constructor must match the SDO_SRID value of the geometries in the table.
The following simple example constructs a point geometry using a well-known text string. (In a WKT, spaces separate ordinates of a vertex, and commas separate vertices.)
SELECT SDO_GEOMETRY('POINT(-79 37)') FROM DUAL;
SDO_GEOMETRY('POINT(-7937)')(SDO_GTYPE, SDO_SRID, SDO_POINT(X, Y, Z), SDO_ELEM_I
--------------------------------------------------------------------------------
SDO_GEOMETRY(2001, NULL, SDO_POINT_TYPE(-79, 37, NULL), NULL, NULL)
Example 2-3 shows SDO_GEOMETRY constructors that create geometry objects, insert the objects into a table, and display the objects that were added to the table.
Example 2-3 SDO_GEOMETRY Constructors to Create Geometries
DECLARE
cola_b_wkb BLOB;
cola_b_wkt_clob CLOB;
cola_b_wkt_varchar VARCHAR2(255);
cola_b_geom SDO_GEOMETRY;
BEGIN
-- Get cola_b geometry into CLOB, VARCHAR2, and BLOB objects,
-- for use by the constructor.
SELECT c.shape.Get_WKT() INTO cola_b_wkt_clob
FROM cola_markets c WHERE c.name = 'cola_b';
cola_b_wkt_varchar := cola_b_wkt_clob;
SELECT c.shape.Get_WKB() INTO cola_b_wkb
FROM cola_markets c WHERE c.name = 'cola_b';
-- Use some SDO_GEOMETRY constructors;
-- insert 3 geometries into the table; display the geometries later.
cola_b_geom := SDO_GEOMETRY(cola_b_wkt_clob);
INSERT INTO cola_markets VALUES (101, 'cola_b_from_clob', cola_b_geom);
cola_b_geom := SDO_GEOMETRY(cola_b_wkt_varchar);
INSERT INTO cola_markets VALUES (102, 'cola_b_from_varchar', cola_b_geom);
cola_b_geom := SDO_GEOMETRY(cola_b_wkb);
INSERT INTO cola_markets VALUES (103, 'cola_b_from_wkb', cola_b_geom);
END;
/
PL/SQL procedure successfully completed.
-- Display the geometries created using SDO_GEOMETRY constructors.
-- All three geometries are identical.
SELECT name, shape FROM cola_markets WHERE mkt_id > 100;
NAME
--------------------------------
SHAPE(SDO_GTYPE, SDO_SRID, SDO_POINT(X, Y, Z), SDO_ELEM_INFO, SDO_ORDINATES)
--------------------------------------------------------------------------------
cola_b_from_clob
SDO_GEOMETRY(2003, NULL, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 1), SDO_ORDINATE_ARR
AY(5, 1, 8, 1, 8, 6, 5, 7, 5, 1))
cola_b_from_varchar
SDO_GEOMETRY(2003, NULL, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 1), SDO_ORDINATE_ARR
AY(5, 1, 8, 1, 8, 6, 5, 7, 5, 1))
cola_b_from_wkb
SDO_GEOMETRY(2003, NULL, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 1), SDO_ORDINATE_ARR
AY(5, 1, 8, 1, 8, 6, 5, 7, 5, 1))