STIsClosed (geometry Data Type)
Returns 1 if the start and end points of the given geometry instance are the same. Returns 1 for geometrycollection types if each contained geometry instance is closed. Returns 0 if the instance is not closed.
The following example creates a LineString instance and uses STIsClosed() to test if the LineString is closed.
DECLARE @g geometry; SET @g = geometry::STGeomFromText('LINESTRING(0 0, 2 2, 1 0)', 0); SELECT @g.STIsClosed();