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Re: Extending my question. Was: The relational model and relational algebra - why did SQL become the industry standard?

From: Jan Hidders <jan.hidders_at_REMOVE.THIS.ua.ac.be>
Date: 10 Mar 2003 18:28:08 +0100
Message-ID: <3e6ccb28.0@news.ruca.ua.ac.be>


Bob Badour wrote:
>
>If you don't mind, I will offer Lauri a little help on this one.

If you think he needs it, by all means.

>From dictionary.com: [...definition snipped...]
>
>A while loop leaves out of consideration several underlying comparison and
>branching operations as well as branching destinations so as to attend to
>the overall operation of repeating a given sequence of steps.
>
>A goto statement is a direct encoding of an unconditional branch as one
>might use in conjunction with comparison operations and conditional branches
>to implement a similar repetition.

Let's see. With GOTOs:

1100 IF NOT(<condition>) THEN GOTO 1210
...
1200 GOTO 1100
1210 ..

With WHILEs:

WHILE <condition> DO
...
END WHILE So those "several underlying comparison and branching operations" you talk about are exactly *two* operations. That's not a lot of abstraction. Certainly not comparable to the kind of abstraction that can be obtained with functions or classes, or the one that is obtained by using a tuple calculus vs. a tuple-set algebra. And since the remark was made in the context of query optimization that should be the amount of abstraction we were talking about when using words like "raising the level of abstraction".

Received on Mon Mar 10 2003 - 11:28:08 CST

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