Groups > comp.databases.ms-sqlserver > #1677

Re: A question about relationship

From	Erland Sommarskog <esquel@sommarskog.se>
Newsgroups	comp.databases.ms-sqlserver
Subject	Re: A question about relationship
Date	2014-02-11 21:54 +0100
Organization	Erland Sommarskog
Message-ID	<XnsA2D1DEE31704BYazorman@127.0.0.1> (permalink)
References	<ldan3d$f0i$1@dont-email.me> <XnsA2D0F0AEE3E6Yazorman@127.0.0.1> <lddcn4$i2b$1@dont-email.me>

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Tony Johansson (johansson.andersson@telia.com) writes:
> Yes a customer without order sounds ok
> But order without customer is incorrect.

I would say that it depends on the business rules. :-) But, yes, it
would be a bit peculiar.

In Northwind CustomerID is nullable, although there is no such order 
in the data. Unfortunately, Northwind leaves a whole lot desired when it 
comes to nullability, indexes etc.

-- 
Erland Sommarskog, Stockholm, esquel@sommarskog.se

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Thread

A question about relationship "Tony Johansson" <johansson.andersson@telia.com> - 2014-02-10 15:18 +0100
  Re: A question about relationship Erland Sommarskog <esquel@sommarskog.se> - 2014-02-10 23:39 +0100
    Re: A question about relationship "Tony Johansson" <johansson.andersson@telia.com> - 2014-02-11 15:39 +0100
      Re: A question about relationship Ross Presser <rpresser@gmail.com> - 2014-02-11 07:11 -0800
        Re: A question about relationship bradbury9 <ray.bradbury9@gmail.com> - 2014-02-11 08:43 -0800
          Re: A question about relationship Ross Presser <rpresser@gmail.com> - 2014-02-11 09:33 -0800
        Re: A question about relationship Lennart Jonsson <erik.lennart.jonsson@gmail.com> - 2014-02-11 18:01 +0100
      Re: A question about relationship Erland Sommarskog <esquel@sommarskog.se> - 2014-02-11 21:54 +0100
        Re: A question about relationship rja.carnegie@gmail.com - 2014-02-11 13:49 -0800
          Re: A question about relationship Erland Sommarskog <esquel@sommarskog.se> - 2014-02-11 23:23 +0100

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