STPointN (geography Data Type)

expression

Is an int expression between 1 and the number of points in the geography instance.

SQL Server return type: geography

CLR return type: SqlGeography

Open Geospatial Consortium (OGC) type: Point

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();

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