Re: Counting propositions
From: Paul G. Brown <paul_geoffrey_brown_at_yahoo.com>
Date: 14 Jun 2004 16:17:41 -0700
Message-ID: <57da7b56.0406141517.9cb7b7d_at_posting.google.com>
Date: 14 Jun 2004 16:17:41 -0700
Message-ID: <57da7b56.0406141517.9cb7b7d_at_posting.google.com>
"x" <x-false_at_yahoo.com> wrote in message news:<40cd9b6a_at_post.usenet.com>...
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> If tuples in a relational relation(ship) (or relvar) are propositions, what
> is the meaning of :
>
> select count(distinct *) as nr
> from <relvar>
>
> and the like ?
Given that all relvars have a key, and assuming that your '*' is a macro that expands to 'all attributes' (don't matter what phase of query processing), then nr is going to equal the number of tuples in the relvar.
In fact, there ought never be any need to do 'distinct' at all. Received on Tue Jun 15 2004 - 01:17:41 CEST