STPointN (geography Data Type)
Returns the specified point in a geography instance.
If a geography instance is user-created, STPointN() returns the point specified by expression by ordering the points in the order in which they were originally input.
If a geography instance is constructed by the system, STPointN() returns the point specified by expression by ordering all the points in the same order they would be output: first by geography instance, then by ring within the instance (if appropriate), and then by point within the ring. This order is deterministic.
If this method is called with a value less than 1, it throws an ArgumentOutOfRangeException.
If this method is called with a value greater than the number of points in the instance, it returns null.
The following example creates a LineString instance and uses STPointN() to retrieve the second point in the description of the instance.
DECLARE @g geography; SET @g = geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326); SELECT @g.STPointN(2).ToString();