STDifference (geometry Data Type)

STDifference (geometry Data Type)

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

.STDifference ( other_geometry )


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

SQL Server return type: geometry

CLR return type: SqlGeometry

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

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

DECLARE @g geometry;
DECLARE @h geometry;
SET @g = geometry::STGeomFromText('POLYGON((0 0, 0 2, 2 2, 2 0, 0 0))', 0);
SET @h = geometry::STGeomFromText('POLYGON((1 1, 3 1, 3 3, 1 3, 1 1))', 0);
SELECT @g.STDifference(@h).ToString();

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