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Minor edits to docs/topics/db/queries.txt.
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@ -140,8 +140,8 @@ To retrieve objects from your database, construct a
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:class:`~django.db.models.Manager` on your model class.
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:class:`~django.db.models.Manager` on your model class.
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A :class:`~django.db.models.query.QuerySet` represents a collection of objects
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A :class:`~django.db.models.query.QuerySet` represents a collection of objects
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from your database. It can have zero, one or many *filters* -- criteria that
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from your database. It can have zero, one or many *filters*. Filters narrow
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narrow down the collection based on given parameters. In SQL terms, a
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down the query results based on the given parameters. In SQL terms, a
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:class:`~django.db.models.query.QuerySet` equates to a ``SELECT`` statement,
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:class:`~django.db.models.query.QuerySet` equates to a ``SELECT`` statement,
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and a filter is a limiting clause such as ``WHERE`` or ``LIMIT``.
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and a filter is a limiting clause such as ``WHERE`` or ``LIMIT``.
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@ -257,10 +257,10 @@ Example::
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These three ``QuerySets`` are separate. The first is a base
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These three ``QuerySets`` are separate. The first is a base
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:class:`~django.db.models.query.QuerySet` containing all entries that contain a
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:class:`~django.db.models.query.QuerySet` containing all entries that contain a
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headline starting with "What". The second is a subset of the first, with an
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headline starting with "What". The second is a subset of the first, with an
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additional criteria that excludes records whose ``pub_date`` is greater than
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additional criteria that excludes records whose ``pub_date`` is today or in the
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now. The third is a subset of the first, with an additional criteria that
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future. The third is a subset of the first, with an additional criteria that
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selects only the records whose ``pub_date`` is greater than now. The initial
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selects only the records whose ``pub_date`` is today or in the future. The
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:class:`~django.db.models.query.QuerySet` (``q1``) is unaffected by the
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initial :class:`~django.db.models.query.QuerySet` (``q1``) is unaffected by the
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refinement process.
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refinement process.
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.. _querysets-are-lazy:
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.. _querysets-are-lazy:
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@ -1079,8 +1079,9 @@ the foreign key aren't saved to the database until you call
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>>> e.blog = some_blog
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>>> e.blog = some_blog
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>>> e.save()
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>>> e.save()
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If a :class:`~django.db.models.ForeignKey` field has ``null=True`` set (i.e., it allows ``NULL``
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If a :class:`~django.db.models.ForeignKey` field has ``null=True`` set (i.e.,
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values), you can assign ``None`` to it. Example::
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it allows ``NULL`` values), you can assign ``None`` to remove the relation.
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Example::
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>>> e = Entry.objects.get(id=2)
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>>> e = Entry.objects.get(id=2)
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>>> e.blog = None
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>>> e.blog = None
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