Returns a copy of the point with the longitude coordinate set to the specified longitude value.
      Syntax
         
            point-expression.ST_Long(DOUBLE longitude_val)
      
      Parameters
         
            - 
               longitude_val – 
               The new longitude value.
            
Returns
         ST_Point Returns a copy of the point with the longitude set to the specified value.
      Standards
         
            SQL/MM (ISO/IEC 13249-3: 2006) Vendor extension