ST_GeomFromWKB function

The ST_GeomFromWKB function takes a well-known binary (WKB) representation of a geometry and, optionally, a spatial reference system identifier as input parameters and returns the corresponding geometry.

If the specified WKB format is null, then null is returned.

The preferred version for this functionality is ST_Geometry.

Syntax

Parameter

wkb: A value of type VARBINARY or BLOB(2G) that contains the well-known binary format of the resulting geometry.
srs_id: A value of type INTEGER that identifies the spatial reference system for the resulting geometry.

If the srs_id parameter is omitted, the spatial reference system with the numeric identifier 4326 is used implicitly.

If the specified srs_id parameter does not identify a spatial reference system listed in the catalog view SYSGEO.ST_SPATIAL_REFERENCE_SYSTEMS, then an error is returned (SQLSTATE 38SU1).

Return type

ST_Geometry

Examples

In the following examples, the lines of results have been reformatted for readability. The spacing in your results will vary according to your online display.

The following code illustrates how the ST_GeomFromWKB function can be used to create and insert a line from a well-known binary (WKB) line representation.

The following example inserts a record into the SAMPLE_GEOMETRIES table with an ID and a geometry in spatial reference system 1 in a WKB format.



CREATE TABLE sample_geometries (id INTEGER, geometry ST_GEOMETRY,
    wkb varbinary(32000))

INSERT INTO sample_geometries(id, geometry)
VALUES
    (1901, ST_GeomFromText('point(1 2)', 1) ),
    (1902, ST_GeomFromText('linestring(33 2, 34 3, 35 6)', 1) ),
    (1903, ST_GeomFromText('polygon((3 3, 4 6, 5 3, 3 3))', 1))

UPDATE sample_geometries AS temp_correlated
SET    wkb = ST_AsBinary(geometry)
WHERE  id = temp_correlated.id

SELECT id, cast(ST_AsText(ST_GeomFromWKB(wkb,1)) AS varchar(190))
   AS geometry
FROM   sample_geometries

Results:


 ID          GEOMETRY                                                                                       
 ----------- ---------------------------------------------------------------
 1901 POINT (1.000000 2.000000)
                                                                                                                               
 1902 LINESTRING (33.000000 2.000000, 34.000000 3.000000, 35.000000 6.000000)
                                                                                  
 1903 POLYGON ((3.000000 3.000000, 5.000000 3.000000, 4.000000 6.000000, 
       3.000000 3.000000))