STLength (geography Data Type)

THIS TOPIC APPLIES TO: yesSQL Server (starting with 2012)noAzure SQL DatabasenoAzure SQL Data Warehouse noParallel Data Warehouse

Returns the total length of the elements in a geography instance or the geography instances within a GeometryCollection.

Syntax


.STLength ( )  

Return Types

SQL Server return type: float

CLR return type: SqlDouble

Remarks

If a geography instance is closed, its length is calculated as the total length around the instance; the length of any polygon is its perimeter, and the length of a point is 0. The length of a GeometryCollection is found by calculating the sum of the lengths of all of the geography instances contained within the collection.

STLength() works on both valid and invalid LineStrings. Typically a LineString is invalid due to overlapping segments, which may be caused by anomalies such as inaccurate GPS traces. STLength() does not remove overlapping or invalid segments. It includes overlapping and invalid segments in the length value that it returns. The MakeValid() method can remove overlapping segments from a LineString.

Examples

The following example creates a LineString instance and uses STLength() to find the length of the instance.

DECLARE @g geography;  
SET @g = geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326);  
SELECT @g.STLength();  

See Also

OGC Methods on Geography Instances