Available in versions: Dev (3.20) | Latest (3.19) | 3.18 | 3.17 | 3.16

ST_NumInteriorRings

Applies to ❌ Open Source Edition   ✅ Express Edition   ✅ Professional Edition   ✅ Enterprise Edition

This function returns the number of interior rings of a polygon geometry. For example:

create.select(stNumInteriorRings(
  stGeomFromText("""
    POLYGON (
      (-3 -3, 3 -3, 3 3, -3 3, -3 -3),
      (-2 -2, 2 -2, 2 2, -2 2, -2 -2),
      (-1 -1, 1 -1, 1 1, -1 1, -1 -1)
    )
  """)
)).fetch();

The result being, for example

+---------------------+
| ST_NumInteriorRings |
+---------------------+
| 2                   |
+---------------------+

To access the Nth interior ring (1-based), use ST_InteriorRingN.

Dialect support

This example using jOOQ:

stNumInteriorRings(geometry)

Translates to the following dialect specific expressions:

Aurora MySQL, Aurora Postgres, CockroachDB, MySQL, Postgres, Redshift, Snowflake

st_numinteriorring(geometry)

MariaDB

st_numinteriorrings(geometry)

Oracle

(
  SELECT (nullif(
    count(*),
    0
  ) - 1)
  FROM table(sdo_util.extract_all(geometry))
)

SQLServer

geometry.STNumInteriorRing()

ASE, Access, BigQuery, DB2, Derby, DuckDB, Exasol, Firebird, H2, HSQLDB, Hana, Informix, MemSQL, SQLDataWarehouse, SQLite, Sybase, Teradata, Trino, Vertica, YugabyteDB

/* UNSUPPORTED */

(These are currently generated with jOOQ 3.20, see #10141), or translate your own on our website

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