Calculates the linear distance between geometries on the surface of the Earth.
      Syntax
         
            geometry-expression.ST_Distance_Spheroid(
                  ST_Geometry
                geo2, VARCHAR(128) unit_name)
      
      Parameters
         
            - 
               geo2 – 
               The other geometry value whose distance is to be measured from the geometry-expression.
            
- 
               unit_name – 
               The linear unit of measure. Defaults to the unit of the spatial reference system.
            
Returns
         DOUBLE Returns the linear distance between geometries on the surface of the Earth calculated in the specified linear units.
      Standards
         
            SQL/MM (ISO/IEC 13249-3: 2006) Vendor extension