Re: Interpretation of Relations

Bob Badour wrote:
> Joe Thurbon wrote:
>

>> Joe Thurbon wrote:
>>
>>> I'm very new to this databases game, and am not even sure I'm using 
>>> the terminology in the right way. I'd like some feedback as to 
>>> whether I'm even in the right ballpark. Most of my understanding of 
>>> the terminology comes from reading this group, and the definitions on 
>>> Wikipedia.
>>
>> Thanks go to all who contributed to this thread. I've got some books 
>> ordered from at local bookstore, and thanks in particular to paul c, 
>> who passed on some really useful references.
>>
>> By the way, I also found my old Uni textbook (ha, I told my wife it 
>> would come in useful one day). It's Fundamentals of Database Systems 
>> by Elmasri and Navathe. Could anyone who is familiar with it give me 
>> some sort of idea about its usefulness. I'm particularly concerned 
>> with page 137:
>>
>> "where each value is an element of dom(Ai) or is a special null value".

One concern is that we're still two chapters away from SQL. Page 137 is within a chapter called "The relational data model and the relational algebra". Although, thinking about it more, my main concern is more adequately reflected in your general caveat below. But yes, you are right.

I vaguely remember the course when I sat for it. One of the most memorable traits of the course was that we _never_ sat in front of a computer with a database installed on it. Never.

>
> One of these days, I really do have to unpack. I am certain I have a
> copy of the book around here somewhere.

I can empathise. One of the side effects of my journey through the relational model is that it has encouraged me to open some of the book boxes I've been avoiding.

>
> One general caveat: Academic books often give rigorous definitions for
> terms that might differ from one text to another. For example, I often
> see contradictory definitions for 'candidate key'. Strangely, some texts
> use the term for teaching about proper superkeys and irreducibility
> while others use the term for teaching about the possibility of multiple
> logical identifiers.
>
> To a certain extent, one has to preface all of those definitions with
> "Within the scope of this book/course".

To me, this is the greatest value of this newsgroup. It allows some discussion of the various definitions terms have, and more importantly discussion of how useful those definitions are in practice.

I'm assuming that as I learn more, the 'greatest value' of the newsgroup will change.

Cheers,
Joe Received on Thu Feb 15 2007 - 21:40:26 CET