Edward Kenworthy <mailto:[EMAIL PROTECTED]> once said:
> On 2/10/03 6:34 pm, "Harkness, David"
> <[EMAIL PROTECTED]> wrote:
>> I have several unidirectional N:1 relations, but I have *zero*
>> relation tables. Granted, they're N:1 and not 1:N, but I don't see
>> how that would make any difference.
>> 
>> MailMessages ---1:N--> Users
>> messageKey             ID
>> ...                    messageKey
>>                        ...
>
> Of course it makes a difference - consider the location and
> number of foreign keys in each case.

How does the choice of unidirectional 1:N vs. N:1 make any difference to
the database schema? The above schema would work for both. Whether the
Users entity has a MailMessagesLocal or the MailMessagesLocal has a
Collection of UsersLocals has no bearing on where you'd put the foreign
key nor force you to use a relation table. Sure, you *could* model it
with a relation table, but why? That would simply turn a N:1 relation
into an N:M relation where M always equals 1.

David Harkness
Sr. Software Engineer
Sony Pictures Digital Networks
(310) 482-4756


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