Descrizione

If the geometry is a polygon or multi-polygon returns the number of rings. Unlike NumInteriorRings, it counts the outer rings as well.

Questa funzione supporta il 3d e non distrugge gli z-index.

Questo metodo supporta le Curve e le Circular String.

Esempi

SELECT ST_NRings(geom) As Nrings, ST_NumInteriorRings(geom) As ninterrings
                                        FROM (SELECT ST_GeomFromText('POLYGON((1 2, 3 4, 5 6, 1 2))') As geom) As foo;
         nrings | ninterrings
--------+-------------
          1 |           0
(1 row)

Si veda anche

ST_NumInteriorRings