ST_InteriorRingN

Returns the Nth interior ring of a polygon.

Usage

geometry ST_InteriorRingN(geom: geometry, n: integer)

Arguments

• geom (geometry): Input geometry
• n (integer)

Description

Returns the Nth interior LINESTRING ring of a POLYGON. Returns NULL if the geometry is not a polygon or n is out of range.

n is 1-based in SedonaDB.

Examples

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
    );

┌──────────────────────────────────────────────────────────────────────────────┐
│ st_interiorringn(st_geomfromtext(Utf8("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 … │
╞══════════════════════════════════════════════════════════════════════════════╡
│ LINESTRING(1 1,2 1,2 2,1 2,1 1)                                              │
└──────────────────────────────────────────────────────────────────────────────┘