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ST_NumInteriorRings

ST_NumInteriorRings returns the number of rings in an input polygon geometry.

Syntax

ST_NumInteriorRings(geom)

Arguments

Return type

INTEGER

If geom is null, then null is returned.

If geom is not a polygon, then null is returned.

Examples

The following SQL returns the number of interior rings in the input polygon.

SELECT ST_NumInteriorRings(ST_GeomFromText('POLYGON((0 0,100 0,100 100,0 100,0 0),(1 1,1 5,5 1,1 1),(7 7,7 8,8 7,7 7))'));

 st_numinteriorrings
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