ST_NumInteriorRing — Returns the number of interior rings (holes) of a Polygon. Alias for ST_NumInteriorRings.
integer ST_NumInteriorRing(geometry a_polygon);
integer ST_NumInteriorRing(
)
This function is an alias for ST_NumInteriorRings.
可用性：1.2.2
ST_NumInteriorRings, ST_InteriorRingN