# STSymDifference (geometry Data Type)

Returns an object representing 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 STSymDistance() 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 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();
```