code: def update_ddl(self, ddl_statements, operation_id=""):
          
          client = self._instance._client
          api = client.database_admin_api
          metadata = _metadata_with_prefix(self.name)
  
          future = api.update_database_ddl(
              self.name, ddl_statements, operation_id=operation_id, metadata=metadata
          )
          return future
docs: Update DDL for this database.
  
          Apply any configured schema from :attr:`ddl_statements`.
  
          See
          https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.database.v1#google.spanner.admin.database.v1.DatabaseAdmin.UpdateDatabase
  
          :type ddl_statements: Sequence[str]
          :param ddl_statements: a list of DDL statements to use on this database
          :type operation_id: str
          :param operation_id: (optional) a string ID for the long-running operation
  
          :rtype: :class:`google.api_core.operation.Operation`
          :returns: an operation instance
          :raises NotFound: if the database does not exist