Definition
ST_NumInteriorRing takes an ST_Polygon and returns the number of its interior rings.
Syntax
Oracle and PostgreSQL
sde.st_numinteriorring (polygon1 sde.st_geometry)
SQLite
st_numinteriorring (polygon1 geometryblob)
Return type
Integer
Example
An ornithologist wants to study a bird population on several south sea islands. She wants to identify which islands contain one or more lakes, because the bird species she is interested in feeds only in freshwater lakes.
The ID and name columns of the islands table identify each island, while the land ST_Polygon column stores the islands' geometry.
Because interior rings represent the lakes, the SELECT statement that includes the ST_NumInteriorRing function lists only those islands that have at least one interior ring.
Oracle
CREATE TABLE islands (
id integer,
name varchar(32),
land sde.st_geometry
);
INSERT INTO islands VALUES (
1,
'Bear',
sde.st_polygon ('polygon ((40 120, 90 120, 90 150, 40 150, 40 120),(50 130, 60 130, 60 140, 50 140, 50 130),(70 130, 80 130, 80 140, 70 140, 70 130))', 4326)
);
INSERT INTO islands VALUES (
2,
'Johnson',
sde.st_polygon ('polygon ((10 10, 50 10, 10 30, 10 10))', 4326)
);
SELECT name
FROM ISLANDS
WHERE sde.st_numinteriorring (land)> 0;
NAME
Bear
PostgreSQL
CREATE TABLE islands (
id integer,
name varchar(32),
land sde.st_geometry
);
INSERT INTO islands VALUES (
1,
'Bear',
sde.st_polygon ('polygon ((40 120, 90 120, 90 150, 40 150, 40 120),(50 130, 60 130, 60 140, 50 140, 50 130),(70 130, 80 130, 80 140, 70 140, 70 130))', 4326)
);
INSERT INTO islands VALUES (
2,
'Johnson',
sde.st_polygon ('polygon ((10 10, 50 10, 10 30, 10 10))', 4326)
);
SELECT name
FROM islands
WHERE sde.st_numinteriorring (land)> 0;
name
Bear
SQLite
CREATE TABLE islands (
id integer,
name varchar(32)
);
SELECT AddGeometryColumn(
NULL,
'islands',
'land',
4326,
'polygon',
'xy',
'null'
);
INSERT INTO islands VALUES (
1,
'Bear',
st_polygon ('polygon ((40 120, 90 120, 90 150, 40 150, 40 120),(50 130, 60 130, 60 140, 50 140, 50 130),(70 130, 80 130, 80 140, 70 140, 70 130))', 4326)
);
INSERT INTO islands VALUES (
2,
'Johnson',
st_polygon ('polygon ((10 10, 50 10, 10 30, 10 10))', 4326)
);
SELECT name
FROM islands
WHERE st_numinteriorring (land)> 0;
name
Bear