ST_NumPoints

Definition

ST_NumPoints returns the number of points (vertices) in an ST_Geometry.

For polygons, both the starting and ending vertices are counted, even though they occupy the same location.

Note that this number is different than the NUMPTS attribute of the ST_Geometry type. The NUMPTS attribute contains a count of the vertices in all the parts of the geometry including separators that occur between parts. There is one separator between each part. For example, a multipart linestring with three parts has two separators. In the NUMPTS attribute, each separator is counted as one vertex. Conversely, the ST_NumPoints function does not include the separators in the vertex count.

Syntax

sde.st_numpoints (g1 sde.st_geometry)

Return type

Integer

Example

The numpoints_test table is created with the geotype column, which contains the ST_Geometry type stored in the g1 geometry column.

The INSERT statements insert a point, a linestring, and a polygon.

Oracle

CREATE TABLE numpoints_test (geotype varchar(12), g1 sde.st_geometry);

INSERT INTO NUMPOINTS_TEST VALUES (
'point',
sde.st_pointfromtext ('point (10.02 20.01)', 0)
);

INSERT INTO NUMPOINTS_TEST VALUES (
'linestring',
sde.st_linefromtext ('linestring (10.02 20.01, 23.73 21.92)', 0)
);

INSERT INTO NUMPOINTS_TEST VALUES (
'polygon',
sde.st_polyfromtext ('polygon ((10.02 20.01, 23.73 21.92, 24.51 12.98,
11.64 13.42, 10.02 20.01))', 0)
);

PostgreSQL

CREATE TABLE numpoints_test (geotype varchar(12), g1 sde.st_geometry);

INSERT INTO numpoints_test VALUES (
'point',
sde.st_point ('point (10.02 20.01)', 0)
);

INSERT INTO numpoints_test VALUES (
'linestring',
sde.st_linestring ('linestring (10.02 20.01, 23.73 21.92)', 0)
);

INSERT INTO numpoints_test VALUES (
'polygon',
sde.st_polygon ('polygon ((10.02 20.01, 23.73 21.92, 24.51 12.98,
11.64 13.42, 10.02 20.01))', 0)
);

The query lists the geometry type and the number of points in each feature.

Oracle

SELECT geotype, sde.st_numpoints (g1) Number_of_points
FROM NUMPOINTS_TEST;

GEOTYPE     Number_of_points

point                       1
linestring                  2
polygon                     5

PostgreSQL

SELECT geotype, sde.st_numpoints (g1) AS Number_of_points
FROM numpoints_test;

geotype     number_of_points

point                       1
linestring                  2
polygon                     5