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Refs #28643 -- Added NullIf database function.

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Thanks Nick Pope, Mariusz Felisiak, and Tim Graham for reviews.
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Mads Jensen 2018-01-14 22:00:16 +01:00 • committed by Tim Graham
parent 217f4456d8
commit 4b9d72210f
6 changed files with 78 additions and 3 deletions
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19
docs/ref/models/database-functions.txt
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@ -149,6 +149,25 @@ will result in a database error.
The PostgreSQL behavior can be emulated using ``Coalesce`` if you know
a sensible maximum value to provide as a default.
``NullIf``
----------
.. class:: NullIf(expression1, expression2)
.. versionadded:: 2.2
Accepts two expressions and returns ``None`` if they are equal, otherwise
returns ``expression1``.
.. admonition:: Caveats on Oracle
Due to an :ref:`Oracle convention<oracle-null-empty-strings>`, this
function returns the empty string instead of ``None`` when the expressions
are of type :class:`~django.db.models.CharField`.
Passing ``Value(None)`` to ``expression1`` is prohibited on Oracle since
Oracle doesn't accept ``NULL`` as the first argument.
.. _date-functions:
Date functions