STDifference (geography Data Type)

Returns an object representing the points from one geography instance that do not lie within another geography instance.


.STDifference ( other_geography )

other_geography

Is another geography instance indicating which points to remove from the instance on which STDifference() is being invoked.

SQL Server return type: geography

CLR return type: SqlGeography

This method always returns null if the spatial reference IDs (SRIDs) of the geography instances do not match.

The following example uses STDifference() to compute the difference between two geography instances.

DECLARE @g geography;
DECLARE @h geography;
SET @g = geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326);
SET @h = geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326);
SELECT @g.STDifference(@h).ToString();

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