def _to_db_str(sequential_list):
    """Convert a list or tuple object to a string of database format."""
    entry_list = []
    for _entry in sequential_list:
        # I know only text type need to be converted by now. More types could
        # be added in the future when we know.
        if isinstance(_entry, str):
            entry_list.append("u'%s'" % _entry)
        else:
            entry_list.append(str(_entry))
    return "(%s)" % ", ".join(entry_list)