Export (0) Print
Expand All
Expand Minimize

STDifference (geometry Data Type)

Returns an object that represents the point set from one geometry instance that does not lie within another geometry instance.

Applies to: SQL Server (SQL Server 2008 through current version), Azure SQL Database.

.STDifference ( other_geometry )

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 result may contain circular arc segments only if the input instances contain circular arc segments.

A. Computing the difference between two Polygon instances

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();

B. Invoking STDifference() on a CurvePolygon instance

The following example uses STDifference() on a CurvePolygon instance.

DECLARE @g geometry = 'CURVEPOLYGON (CIRCULARSTRING (0 -4, 4 0, 0 4, -4 0, 0 -4))';

DECLARE @h geometry = 'POLYGON ((1 -1, 5 -1, 5 3, 1 3, 1 -1))';

-- Note the different results returned by the two SELECT statements

SELECT @h.STDifference(@g).ToString(), @g.STDifference(@h).ToString();

Community Additions

ADD
Show:
© 2014 Microsoft