code: def get_index_field_declaration_list_sql(self, fields):
          
          ret = []
  
          for field in fields:
              ret.append(field)
  
          return ", ".join(ret)
docs: Obtains DBMS specific SQL code portion needed to set an index
          declaration to be used in statements like CREATE TABLE.
  
          :param fields: The columns
          :type fields: list
  
          :rtype: sql