Method explain

django/db/models/sql/query.py:688–698

(self, using, format=None, **options)

        return compiler.has_results()

    def explain(self, using, format=None, **options):
        q = self.clone()
        for option_name in options:
            if (
                not EXPLAIN_OPTIONS_PATTERN.fullmatch(option_name)
                or "--" in option_name
            ):
                raise ValueError(f"Invalid option name: {option_name!r}.")
        q.explain_info = ExplainInfo(format, options)
        compiler = q.get_compiler(using=using)
        return "\n".join(compiler.explain_query())

    def combine(self, rhs, connector):
        """