Re: How will schemas be affected by nested relations?

From: <michael_at_preece.net>
Date: 24 Jul 2006 04:51:44 -0700
Message-ID: <1153741903.993441.45350_at_m79g2000cwm.googlegroups.com>


Marshall wrote:
> How will schema design be affected by having the ability to use
> nested relations? I have an intuition that it might not be that
> much; that nesting is a *little* useful but not all that *much* useful.
> However, I am concerned that I don't have a normal form to
> inform design choices.
>
> When should relation schemas be nested?
>
> I have an idea that the answer might relate to when we use
> ON DELETE CASCADE. If a logical entity has no existence
> without the "enclosing" context of another entity, then it might
> be nested. Another consideration is whether it needs to
> be referred to directly.
>
> For example, an invoice line item without an associated
> invoice doesn't make much sense. However, an invoice
> is probably something we want to keep even if for some
> reason we delete the associated customer. So I can see
> invoice line items as being a candidate for nesting, but
> not invoices.
>
> However I would be much happier if I had a more formal
> treatment than this. Anyone have any references?
>
>
> Marshall

For a more in-depth treatment of this subject please see comp.databases.pick.

;)

PS. G'day Bob. Received on Mon Jul 24 2006 - 13:51:44 CEST

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