Re: 3vl 2vl and NULL - the dead end posting
Date: Tue, 06 Dec 2005 06:18:53 GMT
Message-ID: <h3alf.1657$Of1.376_at_newsread3.news.pas.earthlink.net>
michael_at_preece.net wrote:
> Jonathan Leffler wrote:
>
>
>>michael_at_preece.net wrote: >> >>>David Cressey wrote: >>> >>>>[...] >>> >>>Here's the thing: If you have a table with an unlimited number of rows >>>and a limited number of columns then it is understood that the number >>>of tuples in the table is rows*columns. True? >> >>Not for any definition I've heard of... Did you mean 'values' instead >>of 'tuples'? "The number of values in the table is rows * columns".
>
>
> Yes - kind of, only I really mean the container for a value, rather
> than the value itself. If I'd meant "value" I guess I would have used
> the word "value". Value is a word I'm familiar with - unlike tuple.
> Sorry if I misused the word "tuple". I asked what one of those was a
> while back and ended up thinking of a tuple as like a "cell" in a
> spreadsheet - the intersection of column and row - the container for a
> value or set or scalar or relation. Oh dear - I might have just thrown
> in a few potential bones of contention there. I don't mean to confuse
> anyone. I confess I am unused to these terms and am struggling with a
> foreign language, in a way. Please extend the same courtesy to me as
> you would to someone who is not a native English speaker.
In normal (relational) DBMS jargon, a tuple corresponds (roughly) to a row of cells - in general, to a number of values of a number of different types. There are degenerate cases with zero cells. A value is stored in a cell. The term attribute is often used in this context; speaking a little loosely, it corresponds to either a column name or the place where a value is stored in a tuple as part of a relation.
I would not have guessed that you were not a native speaker of English. Had I done so, I would certainly have been quite so harsh. I probably shouldn't have posted my response anyway, but it's a bit late to worry about that now.
>>>And every tuple must have a value. >> >>Yes - for tuples as tuples, or tuples misreferenced when values was >>intended. Further, the component values in each tuple must have a value. >> >> >>>And if we don't have a actual value for one or more tuples we >>>have to use NULL to represent the fact that there is no value. >> >>IMO, this is so confused between tuples and values that there is no >>value in debating further... :-(
>
>
> OK. OK. Don't spit your dummy so quickly. I wasn't sure I was using the
> right terms. That's why the "OK?" was in there. Thanks for pointing out
> the misuse of a sacrosanct term. You can put your pacifier back in now.
Apologies - I thought I'd deleted that bit. Obviously not...
Unfortunately, you need to use precise terms precisely to avoid confusing people. Tuple does have a generally agreed meaning and it is not 'a place that can store a single value at the intersection of a row and a column in a table'. Hence my confusion.
>>I'm not going to consider the rest of the posting - I would need to >>understand this much of it before going any further, and as you can tell >>from my comments, I don't understand what you've written.
>
>
> You really were doing a marvelous job. I understand it must have very
> been difficult for you - my using "tuple" when I should have used some
> other word. God - how stupid of me. Tut, tut, tut.
I'm not sure how much (justified) sarcasm to read into this, versus jocular self-recrimination. I literally didn't study what you said beyond the point where I stopped because I wasn't sure what your terms of reference were, and it is silly for everyone to spend time arguing using the same words to mean different things.
>>Would you be willing to try again?
>
> Well - yes, if you respond to the full post. Just read "cell" or
> whatever you want for "tuple". It's the intersection of a column and a
> row. The container for a value. OK? And please don't bother responding
> to this post. It'll only become a pointless argument. If you do decide
> to address the same post again, please don't snip so heavily. It's
> often really annoying when people remove content that is, or becomes,
> relevant to the discussion as it evolves.
Well, I am responding (with changed subject to indicate that it might just conceivably be the end of the this part of the thread).
I chopped ruthlessly because the remainder of the message was not relevant to my questioning - and will continue to do chop heavily when it seems appropriate to me. I gave enough context for my remarks to be comprehensible (I dislike postings with zero context), but I equally dislike postings that contain too much irrelevant material.
-- Jonathan Leffler #include <disclaimer.h> Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com Guardian of DBD::Informix v2005.02 -- http://dbi.perl.org/Received on Tue Dec 06 2005 - 07:18:53 CET