ST_Dimension function

The ST_Dimension function takes a geometry as an input parameter and returns its dimension.

If the given geometry is empty, then -1 is returned. For points and multipoints, the dimension is 0 (zero); for curves and multicurves, the dimension is 1; and for polygons and multipolygons, the dimension is 2. If the given geometry is null, then null is returned.

This function can also be called as a method.

Syntax

Parameter

geometry: A value of type ST_Geometry that represents the geometry for which the dimension is returned.

Return type

INTEGER

Example

This example creates several different geometries and finds their dimensions.


SET CURRENT FUNCTION PATH = CURRENT FUNCTION PATH, db2gse
CREATE TABLE sample_geoms (id char(15), geometry ST_Geometry)

INSERT INTO sample_geoms VALUES
       ('Empty Point', ST_Geometry('point EMPTY',0))

INSERT INTO sample_geoms VALUES
       ('Point ZM', ST_Geometry('point zm (10 10 16 30)' ,0))

INSERT INTO sample_geoms VALUES
       ('MultiPoint M', ST_Geometry('multipoint m (10 10 5, 
         50 10 6, 10 30 8)' ,0))

INSERT INTO sample_geoms VALUES
       ('LineString', ST_Geometry('linestring (10 10, 15 20)',0))

INSERT INTO sample_geoms VALUES
       ('Polygon', ST_Geometry('polygon((40 120, 90 120, 90 150, 
         40 150, 40 120))' ,0))

SELECT id, ST_Dimension(geometry)  Dimension
FROM sample_geoms

Results:


ID              DIMENSION
--------------- -----------
Empty Point              -1
Point ZM                  0
MultiPoint M              0
LineString                1
Polygon                   2