operations.py 文件源码

def force_no_ordering(self):
        """
        "ORDER BY NULL" prevents MySQL from implicitly ordering by grouped
        columns. If no ordering would otherwise be applied, we don't want any
        implicit sorting going on.
        """
        if django.VERSION >= (1, 8):
            return [(None, ("NULL", [], False))]
        else:
            return ["NULL"]