STIsEmpty (geometry Data Type)
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Returns 1 if a geometry instance is empty. Returns 0 if a geometry instance is not empty.
Syntax
.STIsEmpty ( )
Return Types
SQL Server return type: bit
CLR return type: SqlBoolean
Examples
The following example creates an empty geometry instance and uses STIsEmpty() to test whether the instance is empty.
DECLARE @g geometry;
SET @g = geometry::STGeomFromText('POLYGON EMPTY', 0);
SELECT @g.STIsEmpty();