Source code for forml.io.dsl.function._window

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"""
Functions that perform calculations across rows of the query result.

Todo:
    Support for window functions is experimental and unlikely to be supported by the existing
    parsers.

These function needs to be wrapped as a valid :class:`dsl.Feature <forml.io.dsl.Feature>` using the
:class:`dsl.Window <forml.io.dsl.Window>` API.


Aggregate Functions
-------------------

All :ref:`Aggregate functions <query-functions-aggregate>` can be used as window functions by
calling the :meth:`.over() <forml.io.dsl.Window.Function.over>` method.

Ranking Functions
-----------------
"""

from .._struct import kind as kindmod
from .._struct import series


[docs]class RowNumber(series.Window.Function):
    """A unique sequential number for each row starting from one according to the ordering of rows
    within the window partition.

    Examples:
        >>> ETL = Student.select(function.RowNumber().over(Student.surname))
    """

    kind: kindmod.Integer = kindmod.Integer()