Re: Requirements for update languages?
From: Jan Hidders <hidders_at_REMOVE.THIS.uia.ua.ac.be>
Date: 15 Nov 2002 13:50:36 +0100
Message-ID: <3dd4ed9c$1_at_news.uia.ac.be>
Date: 15 Nov 2002 13:50:36 +0100
Message-ID: <3dd4ed9c$1_at_news.uia.ac.be>
Lauri Pietarinen wrote:
>
>One further observation came to mind:
>
>With the bag-representation you just mentioned it is possible to
>remove the duplicates, or reduce the number of them just by
>"updating" the counter. This is not possible in SQL (without
>some internal rowid).
>
>So would it be fair to say that SQL does not even really adher to
>a bag-model?
If you mean that as a bag calculus it has some very obvious short-comings and cannot even express certain things that can be expressed with SQL if you simulate the bags with sets of element-cardinality pairs, then, yes, you are right.
- Jan Hidders