stboundary-geometry-data-type.md

title	STBoundary (geometry Data Type)
description	STBoundary (geometry Data Type)
author	MladjoA
ms.author	mlandzic
ms.date	03/14/2017
ms.service	sql
ms.subservice	t-sql
ms.topic	reference
ms.custom	ignite-2025
f1_keywords	STBoundary (geometry Data Type) STBoundary_TSQL
helpviewer_keywords	STBoundary (geometry Data Type)
dev_langs	TSQL
monikerRange	=azuresqldb-current || >=sql-server-2016 || >=sql-server-linux-2017 || =azuresqldb-mi-current || =fabric-sqldb

STBoundary (geometry Data Type)

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

Returns the boundary of a geometry instance.

Syntax

  
.STBoundary ( )  

Return Types

[!INCLUDEssNoVersion] 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();

See Also

OGC Methods on Geometry Instances