OpenGIS proposes a number of other functions that can produce geometries. They are designed to implement spatial operators.
These functions are not implemented in MySQL. They may appear in future releases.
              Returns a geometry that represents all points whose
              distance from the geometry value
              g is less than or equal to a
              distance of d.
            
              Returns a geometry that represents the convex hull of the
              geometry value g.
            
              Returns a geometry that represents the point set
              difference of the geometry value
              g1 with
              g2.
            
              Returns a geometry that represents the point set
              intersection of the geometry values
              g1 with
              g2.
            
              Returns a geometry that represents the point set symmetric
              difference of the geometry value
              g1 with
              g2.
            
              Returns a geometry that represents the point set union of
              the geometry values g1 and
              g2.
            

