ST_Centroid

ST_Centroid takes a geometry as an input parameter and returns the geometric center, which is the center of the minimum bounding rectangle of the given geometry, as a point. The resulting point is represented in the spatial reference system of the given geometry.

If the given geometry is null or is empty, then null is returned.

Syntax

Parameter

geometry: A value of one of the seven distinct spatial data types that represents the geometry to determine the geometric center.

Return type

db2gse.ST_Point

Example

This example creates two geometries and finds the centroid of them.


SET CURRENT FUNCTION PATH = CURRENT FUNCTION PATH, db2gse
CREATE TABLE sample_geoms (id INTEGER, geometry ST_Geometry)

INSERT INTO sample_geoms VALUES
    (1, ST_Polygon('polygon
    ((40 120, 90 120, 90 150, 40 150, 40 120),
    (50 130, 80 130, 80 140, 50 140, 50 130))',0))

INSERT INTO sample_geoms VALUES
    (2, ST_MultiPoint('multipoint(10 10, 50 10, 10 30)' ,0))


SELECT id, CAST(ST_AsText(ST_Centroid(geometry)) 
   as VARCHAR(40)) Centroid
FROM sample_geoms

Results:


ID          CENTROID
----------- ----------------------------------------
          1 POINT ( 65.00000000 135.00000000)
          2 POINT ( 30.00000000 20.00000000)