STDifference (geometry Data Type)
Returns an object representing the points from one geometry instance that do not lie within another geometry instance.
Syntax
.STDifference (other_geometry)
Arguments
- other_geometry
Is another geometry instance indicating which points to remove from the instance on which STDifference() is being invoked.
Return Types
SQL Server return type: geometry
CLR return type: SqlGeometry
Remarks
This method always returns null if the spatial reference IDs (SRIDs) of the geometry instances do not match.
Examples
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();