STBoundary (geometry Data Type)

**APPLIES TO:** ![yes](media/yes.png)SQL Server (starting with 2008) ![yes](media/yes.png)Azure SQL Database ![no](media/no.png)Azure SQL Data Warehouse ![no](media/no.png)Parallel Data Warehouse

Returns the boundary of a geometry instance.

Syntax

  
.STBoundary ( )

Return Types

SQL Server return type: geometry

CLR return type: SqlGeometry

Remarks

STBoundary() returns an empty GeometryCollection when the endpoints for a LineString, CircularString, or CompoundCurve instance are the same.

Examples

A. Using STBoundary() on a LineString instance with different endpoints

The following example creates a LineString``geometry instance. STBoundary() returns the boundary of the LineString.

DECLARE @g geometry;  
SET @g = geometry::STGeomFromText('LINESTRING(0 0, 2 2, 0 2, 2 0)', 0);  
SELECT @g.STBoundary().ToString();

B. Using STBoundary() on a LineString instance with the same endpoints

The following example creates a valid LineString instance with the same endpoints. STBoundary() returns an empty GeometryCollection.

 DECLARE @g geometry;  
 SET @g = geometry::STGeomFromText('LINESTRING(0 0, 2 2, 0 2, -2 2, 0 0)', 0);  
 SELECT @g.STBoundary().ToString();

C. Using STBoundary() on a CurvePolygon instance

The following example uses STBoundary() on a CurvePolygon instance. STBoundary() returns a CircularString instance.

 DECLARE @g geometry;  
 SET @g = geometry::STGeomFromText('CURVEPOLYGON(CIRCULARSTRING(0 0, 2 2, 0 2, -2 2, 0 0))', 0);  
 SELECT @g.STBoundary().ToString();