code: def dttm_sql_literal(self, dttm, is_epoch_in_utc):
          
          tf = self.python_date_format
          if self.database_expression:
              return self.database_expression.format(dttm.strftime('%Y-%m-%d %H:%M:%S'))
          elif tf:
              if is_epoch_in_utc:
                  seconds_since_epoch = dttm.timestamp()
              else:
                  seconds_since_epoch = (dttm - datetime(1970, 1, 1)).total_seconds()
              seconds_since_epoch = int(seconds_since_epoch)
              if tf == 'epoch_s':
                  return str(seconds_since_epoch)
              elif tf == 'epoch_ms':
                  return str(seconds_since_epoch * 1000)
              return "'{}'".format(dttm.strftime(tf))
          else:
              s = self.table.database.db_engine_spec.convert_dttm(
                  self.type or '', dttm)
              return s or "'{}'".format(dttm.strftime('%Y-%m-%d %H:%M:%S.%f'))
docs: Convert datetime object to a SQL expression string
  
          If database_expression is empty, the internal dttm
          will be parsed as the string with the pattern that
          the user inputted (python_date_format)
          If database_expression is not empty, the internal dttm
          will be parsed as the sql sentence for the database to convert