code: def get_unique_constraint_declaration_sql(self, name, index):
          
          columns = index.get_quoted_columns(self)
          name = Identifier(name)
  
          if not columns:
              raise DBALException('Incomplete definition. "columns" required.')
  
          return "CONSTRAINT %s UNIQUE (%s)%s" % (
              name.get_quoted_name(self),
              self.get_index_field_declaration_list_sql(columns),
              self.get_partial_index_sql(index),
          )
docs: Obtains DBMS specific SQL code portion needed to set a unique
          constraint declaration to be used in statements like CREATE TABLE.
  
          :param name: The name of the unique constraint.
          :type name: str
  
          :param index: The index definition
          :type index: Index
  
          :return: DBMS specific SQL code portion needed to set a constraint.
          :rtype: str