The ST_IsEmpty() function

The CREATE TABLE statement below creates the empty_test table with geotype, which stores the data type of the subclasses that are stored in the g1 ST_Geometry column:

CREATE TABLE empty_test (geotype varchar(20),
                         g1      ST_Geometry);

The following INSERT statements insert two records each for the geometry subclasses: point, linestring, and polygon; one record is empty and one is not:

INSERT INTO empty_test VALUES( 
    'Point', ST_PointFromText('point (10.02 20.01)',1000) 
);

INSERT INTO empty_test VALUES( 
    'Point', ST_PointFromText('point empty',1000) 
);

INSERT INTO empty_test VALUES( 
    'Linestring', 
    ST_LineFromText('linestring (10.02 20.01,10.32 23.98,11.92 25.64)',1000) 
);

INSERT INTO empty_test VALUES( 
   'Linestring',
   ST_LineFromText('linestring empty',1000) 
);

INSERT INTO empty_test VALUES( 
    'Polygon', 
    ST_PolyFromText('polygon ((10.02 20.01,11.92 35.64,25.02
34.15,19.15 33.94,10.02 20.01))',1000) 
);

INSERT INTO empty_test VALUES( 
    'Polygon',
    ST_PolyFromText('polygon empty',1000) 
);

The query returns the geometry type from the geotype column and the results of the ST_IsEmpty() function:

SELECT geotype, ST_IsEmpty(g1) Is_it_empty 
   FROM empty_test


geotype              is_it_empty 

Point                          f
Point                          t
Linestring                     f
Linestring                     t
Polygon                        f
Polygon                        t