Fixed some stale documentation that was advising against the use of...

the database. Every addition, creation and deletion is immediately and

automatically saved to the database.

One-to-one relationships

------------------------

One-to-one relationships are very similar to Many-to-one relationships.

If you define a OneToOneField on your model, instances of that model will have 

access to the related object via a simple attribute of the model.

For example::

    class EntryDetail(models.Model):

        entry = models.OneToOneField(Entry)

        details = models.TextField()

    ed = EntryDetail.objects.get(id=2)

    ed.entry # Returns the related Entry object.

The difference comes in reverse queries. The related model in a One-to-one

relationship also has access to a ``Manager`` object; however, that ``Manager``

represents a single object, rather than a collection of objects::

    e = Entry.objects.get(id=2)

    e.entrydetail # returns the related EntryDetail object

If no object has been assigned to this relationship, Django will raise

a ``DoesNotExist`` exception.

Instances can be assigned to the reverse relationship in the same way as 

you would assign the forward relationship::

    e.entrydetail = ed

Many-to-many relationships

--------------------------

``related_name='entries'``, then each ``Author`` instance would have an

``entries`` attribute instead of ``entry_set``.

One-to-one relationships

------------------------

The semantics of one-to-one relationships will be changing soon, so we don't

recommend you use them.

How are the backward relationships possible?

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