stsymdifference-geometry-data-type.md

title	STSymDifference (geometry Data Type)
description	STSymDifference (geometry Data Type)
author	MladjoA
ms.author	mlandzic
ms.date	02/06/2020
ms.service	sql
ms.subservice	t-sql
ms.topic	reference
ms.custom	ignite-2025
f1_keywords	STSymDifference_TSQL STSymDifference (geometry Data Type)
helpviewer_keywords	STSymDifference (geometry Data Type)
dev_langs	TSQL
monikerRange	=azuresqldb-current || >=sql-server-2016 || >=sql-server-linux-2017 || =azuresqldb-mi-current || =fabric-sqldb

STSymDifference (geometry Data Type)

[!INCLUDE SQL Server Azure SQL Database Azure SQL Managed Instance FabricSQLDB]

Returns an object that represents all points that are either in one geometry instance or another geometry instance, but not those points that lie in both instances.

Syntax

  
.STSymDifference ( other_geometry )  

Arguments

other_geometry
Is another geometry instance in addition to the instance on which STSymDifference() is being invoked.

Return Types

[!INCLUDEssNoVersion] 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. The result may contain circular arc segments only if the input instances contain circular arc segments.

Examples

A. Computing the symmetric difference of two Polygon instances

The following example uses STSymDifference() to compute the symmetric difference of two Polygon instances.

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.STSymDifference(@h).ToString();  

B. Computing the symmetric difference between a CurvePolygon and a Polygon instance

The following example returns a GeometryCollection that represents the symmetric difference between a CurvePolygon and a Polygon.

 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))';  
 SELECT @h.STSymDifference(@g).ToString();

C. Using STSymDifference() on CurvePolygon instance with an inscribed Polygon instance

The following example returns a CurvePolygon instance with an interior Polygon ring that represents the symmetric difference between the two instances compared.

 DECLARE @g geometry = 'CURVEPOLYGON (CIRCULARSTRING (0 -4, 4 0, 0 4, -4 0, 0 -4))';  
 DECLARE @h geometry = 'POLYGON ((1 -1, 2 -1, 2 1, 1 1, 1 -1))';  
 SELECT @h.STSymDifference(@g).ToString();

See Also

OGC Methods on Geometry Instances