Re: Relation Definition

From: Alfredo Novoa <alfredo_novoa_at_hotmail.com>
Date: Mon, 21 Feb 2005 16:12:58 +0100
Message-ID: <sfuj11hc5iugpa6uaug9h2acuqvjvjip28@4ax.com>

On Fri, 18 Feb 2005 21:33:50 GMT, Jan Hidders <jan.hidders_at_REMOVETHIS.pandora.be> wrote:

>>>Def. [Tuple] A *tuple* is a partial function that maps column names to
>>>domain values and is defined for a finite set of column names which is
>>>called its *header*.
>>
>> In which way is "columnar" a tuple "column"?
>
>You mean, why did I say "column name" and not just "field name"?

Yes. Or just "attribute name".

> Because
> the field names in these tuples must be valid column names.

But tuples don't have columns, and you have not defined what a column is.

BTW a header is not a set of column or attribute names, it is a set of name and domain pairs.

Regards Received on Mon Feb 21 2005 - 09:12:58 CST