Syntax
------ 
Polygon(ls1,ls2,...)
 
Description
----------- 
Constructs a WKB Polygon value from a number of WKB
LineString
arguments. If any argument does not represent the WKB of a
LinearRing (that is,
not a closed and simple LineString) the return value is
NULL.
 
Note that according to the OpenGIS standard, a POLYGON
should have exactly one ExteriorRing and all other rings
should lie within that ExteriorRing and thus be the
InteriorRings. Practically, however, some systems, including
MariaDB's, permit polygons to have several
'ExteriorRings'. In the case of there being multiple,
non-overlapping exterior rings ST_NUMINTERIORRINGS() will
return 1.
 
Examples
-------- 
SET @g = ST_GEOMFROMTEXT('POLYGON((1 1,1 5,4 9,6 9,9 3,7
2,1 1))');
 
CREATE TABLE gis_polygon (g POLYGON);
INSERT INTO gis_polygon VALUES
 (PolygonFromText('POLYGON((10 10,20 10,20 20,10 20,10
10))')),
 (PolyFromText('POLYGON((0 0,50 0,50 50,0 50,0 0), (10
10,20 10,20 20,10 20,10 10))')),
 (PolyFromWKB(AsWKB(Polygon(LineString(Point(0, 0),
Point(30, 0), Point(30, 30), Point(0, 0))))));
 
Non-overlapping 'polygon':
 
SELECT ST_NumInteriorRings(ST_PolyFromText('POLYGON((0 0,10
0,10 10,0 10,0 0),
 (-1 -1,-5 -1,-5 -5,-1 -5,-1 -1))')) AS NumInteriorRings;
 
+------------------+
| NumInteriorRings |
+------------------+
| 1 |
+------------------+
 

 
 
 
 
 
 
 

URL: https://mariadb.com/kb/en/polygon/