Re: A new proof of the superiority of set oriented approaches: numerical/time serie linear interpolation

From: Jon Heggland <jon.heggland_at_idi.ntnu.no>
Date: Thu, 03 May 2007 16:47:21 +0200
Message-ID: <f1csoq$p68$1@orkan.itea.ntnu.no>

Bob Badour wrote:
> Jon Heggland wrote:

>> As for variables being inherent to RT ... You can discuss relational
>> algebra without mentioning variables; the algebra is only concerned with
>> values.

>
> I disagree. Algebra is all about variables and symbolic manipulation of
> variables. When we talk about an algebraic formula for a straight line
> with slope m and y-intercept b: y = mx + b, we are discussing variables
> x and y. When we talk about the generalization of all such lines, m and
> b become variables too.

Fine. All the more reasons to talk about variables. :) I only meant to express something like this:

"[T]he [relational algebra] operators are all /read only/ (i.e., they 'read' but do not update their operands). Thus, they apply specifically to /values/---relation values, of course---and hence, harmlessly, to those relation values that happen to be the current values of relvars." (C. J. Date, An Introduction to Database Systems, 8th ed.)

Never mind.

-- 
Jon

Received on Thu May 03 2007 - 09:47:21 CDT