Returns a specified geometry in a geometry collection.
.STGeometryN ( expression ) expression
Is an int expression between 1 and the number of geometry instances in the geometrycollection.
SQL Server return type: geometry
CLR return type: SqlGeometry
This method returns null if the parameter is larger than the result of STNumGeometries() and will throw an ArgumentOutOfRangeException if the expression parameter is less than 1.
The following example creates a MultiPoint``geometry collection and uses STGeometryN() to find the second geometry instance of the collection.
DECLARE @g geometry;
SET @g = geometry::STGeomFromText('MULTIPOINT(0 0, 13.5 2, 7 19)', 0);
SELECT @g.STGeometryN(2).ToString();