docs: def result(self, *args, **kwargs):
          """
          Construye la consulta SQL
          """
          prettify = kwargs.get('pretty', False)
          self.__prepareData__()
          sql = 'SELECT '
          sql +=  ', '.join(self.fields)
          
          if len(self.tables) > 0:
              if prettify:
                  sql += '\n'
              else:
                  sql += ' '
              sql +=  'FROM '
              sql +=  ', '.join(self.tables)
          if self.where_criteria.size() > 0:
              if prettify:
                  sql += '\n'
              else:
                  sql += ' '
              sql +=  'WHERE '
              sql +=  self.where_criteria.result()
          if len(self.group_fields) > 0:
              if prettify:
                  sql += '\n'
              else:
                  sql += ' '
              sql +=  'GROUP BY '
              sql +=  ', '.join(self.group_fields)
          if len(self.order_by_fields) > 0:
              if prettify:
                  sql += '\n'
              else:
                  sql += ' '
              sql +=  'ORDER BY '
              sql +=  ', '.join(self.order_by_fields)
              if prettify:
                  sql += '\n'
              else:
                  sql += ' '
  
          return sql