Re: More on identifiers

On Tue, 09 Jun 2009 14:50:02 +1000, David BL <davidbl_at_iinet.net.au> wrote:

> On Jun 9, 10:22 am, "Joe Th

[snip patient explanation - thanks]

>
> So assuming you mean database variables, you have indeed misunderstood
> something, because an "inner database" is treated as a value of an
> attribute of a tuple within the containing "outer database". The
> "inner database" doesn't imply the existence of an associated
> variable.

That was the bit I missed. (Well, that and the more general reason for using abstract identifiers, which you clarified above).

> That indeed is the whole point to how they are able to
> eliminate variables from the logical model.
>
[...]
>
> So to make it clear, I'm suggesting that there is only /one/ database
> variable in the scenario of recording all the information about the
> items in a physical database.
>

That wasn't clear to me from your original post. Thanks for taking the time to clear it up for me.

>> I'm pretty sure I'm missing something. (I wonder how embarrassing it
>> will
>> be when you point it out).

Hmm, it was only a little embarrassing.

[...]

>
> I would say rather informally that logical models can compose by using
> DVAs.
>

Now that I understand the above, that makes sense to me now.

Thanks again,
Joe Received on Tue Jun 09 2009 - 07:35:39 CEST