ST_InteriorRingN - Wherobots

Returns the Nth (1-based) interior linestring ring of the polygon geometry. Returns NULL if the geometry is not a polygon or the given N is out of range

The index is 1-based: n = 1 returns the first interior ring; zero, negative, or out-of-range indices return NULL. When migrating from a runtime with zero-based indices, add 1 to the old index. See Geometry and raster API migration.

Signatures

ST_InteriorRingN(geom: Geometry, n: Integer)

Parameters

Geometry

required

The input geometry.

Integer

required

The 1-based index of the interior ring.

Return type

The resulting geometry.

Example

SELECT ST_InteriorRingN(ST_GeomFromText('POLYGON((0 0, 0 5, 5 5, 5 0, 0 0), (1 1, 2 1, 2 2, 1 2, 1 1), (1 3, 2 3, 2 4, 1 4, 1 3), (3 3, 4 3, 4 4, 3 4, 3 3))'), 1)

LINESTRING (1 1, 2 1, 2 2, 1 2, 1 1)

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Signatures

Parameters

Return type

Example