Nome
ST_NumGeometries — Restituisce TRUE se la geometria è una geometrycollection, un poligono o un punto vuoto, ecc.
Sinossi
integer ST_NumGeometries(geometry geom);
Descrizione
Returns the number of elements in a geometry collection (GEOMETRYCOLLECTION or MULTI*). For non-empty atomic geometries returns 1. For empty geometries returns 0.
Migliorato: Nella 2.0.0 è stato introdotto il supporto per le superfici poliedriche, i triangoli e i TIN.
Changed: 2.0.0 In prior versions this would return NULL if the geometry was not a collection/MULTI type. 2.0.0+ now returns 1 for single geometries e.g POLYGON, LINESTRING, POINT.
Changed: 3.6.0 TIN and PolyhedralSurface are treated as unitary geometries and return 1; use ST_NumPatches to count faces.
Questo metodo implementa la specifica SQL/MM. SQL-MM 3: 9.1.4
Questa funzione supporta il 3d e non distrugge gli z-index.
Questa funzione supporta le Polyhedral Surface.
Questa funzione supporta i Triangoli e le Triangulated Irregular Network Surfaces (TIN).
Esempi
This example returns 1; prior versions would have returned NULL.
SELECT ST_NumGeometries('LINESTRING(77.29 29.07,77.42 29.26,77.27 29.31,77.29 29.07)');
st_numgeometries
------------------
1
(1 row)
A MultiPoint counts as one geometry within a GeometryCollection.
SELECT ST_NumGeometries('GEOMETRYCOLLECTION(MULTIPOINT((-2 3),(-2 2)),
LINESTRING(5 5,10 10),
POLYGON((-7 4.2,-7.1 5,-7.1 4.3,-7 4.2)))');
st_numgeometries
------------------
3
(1 row)