ST_IsEmpty function

The ST_IsEmpty function takes a geometry as an input parameter and returns 1 if the specified geometry is empty. Otherwise 0 (zero) is returned.

If the specified geometry is null, then null is returned.

Syntax

Parameter

geometry: A value of type ST_Geometry or one of its subtypes that represents the geometry that is to be tested.

Return type

INTEGER

Example

The following code creates three geometries and then determines if they are empty.


CREATE TABLE sample_geoms (id INTEGER, geometry ST_Geometry)

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

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

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

INSERT INTO sample_geoms VALUES
       (4, ST_Geometry('linestring z (10 10 166, 20 10 168)',0))

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


SELECT id, ST_IsEmpty(geometry)  Is_Empty
FROM sample_geoms

Results:


ID          IS_EMPTY
----------- -----------
          1           1
          2           0
          3           0
          4           0
          5           0