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16.5.3 Functions That Create New Geometries from Existing Ones »
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16.5.2.7. GeometryCollection Functions

These functions return properties of GeometryCollection values.

  • GeometryN(gc,N)

    Returns the N-th geometry in the GeometryCollection value gc. Geometries are numbered beginning with 1. 

    mysql> SET @gc = 'GeometryCollection(Point(1 1),LineString(2 2, 3 3))';
mysql> SELECT AsText(GeometryN(GeomFromText(@gc),1));
+----------------------------------------+
| AsText(GeometryN(GeomFromText(@gc),1)) |
+----------------------------------------+
| POINT(1 1)                             |
+----------------------------------------+

  • NumGeometries(gc)

    Returns the number of geometries in the GeometryCollection value gc. 

    mysql> SET @gc = 'GeometryCollection(Point(1 1),LineString(2 2, 3 3))';
mysql> SELECT NumGeometries(GeomFromText(@gc));
+----------------------------------+
| NumGeometries(GeomFromText(@gc)) |
+----------------------------------+
|                                2 |
+----------------------------------+