elements.py 文件源码

def __init__(self, func, partition_by=None, order_by=None):
        """Produce an :class:`.Over` object against a function.

        Used against aggregate or so-called "window" functions,
        for database backends that support window functions.

        E.g.::

            from sqlalchemy import over
            over(func.row_number(), order_by='x')

        Would produce "ROW_NUMBER() OVER(ORDER BY x)".

        :param func: a :class:`.FunctionElement` construct, typically
         generated by :data:`~.expression.func`.
        :param partition_by: a column element or string, or a list
         of such, that will be used as the PARTITION BY clause
         of the OVER construct.
        :param order_by: a column element or string, or a list
         of such, that will be used as the ORDER BY clause
         of the OVER construct.

        This function is also available from the :data:`~.expression.func`
        construct itself via the :meth:`.FunctionElement.over` method.

        .. versionadded:: 0.7

        """
        self.func = func
        if order_by is not None:
            self.order_by = ClauseList(
                *util.to_list(order_by),
                _literal_as_text=_literal_as_label_reference)
        if partition_by is not None:
            self.partition_by = ClauseList(
                *util.to_list(partition_by),
                _literal_as_text=_literal_as_label_reference)