code: def _compile_update_wheres(self, query):
          
          base_where = self._compile_wheres(query)
  
          if not query.joins:
              return base_where
  
          join_where = self._compile_update_join_wheres(query)
  
          if not base_where.strip():
              return "WHERE %s" % self._remove_leading_boolean(join_where)
  
          return "%s %s" % (base_where, join_where)
docs: Compile the additional where clauses for updates with joins.
  
          :param query: A QueryBuilder instance
          :type query: QueryBuilder
  
          :return: The compiled sql
          :rtype: str