[Year 12 IT Apps] IT Apps Exam, Short Answer, Question 7A

[Gary Vear]

Thanks, Mark. Provided you’re correct, then you’ve only confirmed my fears. Some of my students probably had trouble resisting the logical inclination to create a separate table to address the 2nd repeating field. 

 

I agree with everything you’ve written below, which means I wasn’t confused by question per se. Instead, I was more confused by the fact the examiners expected students to craft such an unrealistic response to demonstrate their understanding of 1NF. Surely there are better, more realistic ways to demonstrate this.

 

From: itapps-bounces at edulists.com.au [mailto:itapps-bounces at edulists.com.au] On Behalf Of Mark
Sent: Monday, November 10, 2014 4:44 PM
To: Year 12 IT Applications Teachers' Mailing List
Subject: Re: [Year 12 IT Apps] IT Apps Exam, Short Answer, Question 7A

 

From: itapps-bounces at edulists.com.au [mailto:itapps-bounces at edulists.com.au] On Behalf Of Vear, Gary D

 

 

Will students be penalised if they do the sensible thing and normalise this data to 2NF by creating separate tables?

I'd appreciate feedback/corrections from others on this question, since it has me somewhat confused.

 

I fear that a student who (logically and properly) translated the table to 2NF would be penalised since the question asked for knowledge of 1NF.

Any 1NF solution (with a single, ugly table) would be technically correct (no repeating fields, one datum per field) but completely useless as a table.

 

That's what chews my Chihuahuas. 

 

Normalising to 1NF is a completely artificial exercise. Normalisation is a destination, and the 1,2,3 steps are purely logical - not practical - stages, simply to aid theoretical elucidation. 

 

In practice, you never start with 1NF, proceed to 2 and fix things up with 3.

 

For a start, 2NF problems are never even going to happen if you start every new table with a key field.  

Bang. 

Problem solved. 

No multiple-field keys, so no 2NF issues. 

 

If you start a database design with an understanding of 2NF you never need to experience 2NF problems. 

I know theoretically that falling into an open sewer is not good. I don't need to be pushed into the cesspit to see if I know how to get out.

I side-step it before I get to it.

 

Similarly, you don't start a database by throwing fields together carelessly and then sorting problems out later, step by step.

 

Slave: Here, mighty Pharaoh. We have finished your million-ton tomb.

Pharaoh: O goody. Does it have a burial chamber in it?

Slave: O dear. Give us twenty years. We'll fix it. Then you can ask if the pointy end is at the top or not.

 

I know that the examiners want to test whether students understand the logic behind attaining 1NF. 

That's great. I love them for it.

Capable students could easily and quickly have shown their understanding of 1NF in this exam if they'd been given a a table with one repeating field.

 

But to add the second repeating field? That was just ugly and unnecessary.

 

Student: "Of course I know 1NF. I split the repeating values into new records... but what the hell do I do with the second repeating field? I can't meaningfully fix that with a single table. I'd need to get to 2NF to do that. I can't do anything sensible with a single table. What am I supposed to do? OK. I'll go to 2NF and lose all my marks..."


The question mistakenly assumed that having 2 repeating fields would be twice as hard as having 1 repeating field.  


Wrong. The level of difficulty was exponential, not additive 

 

I feel better now.

 

-- 

 

Mark Kelly

mark AT vceit DOT com

http://vceit.com

 

I love the sound of people's voices after they stop talking.

 

I, Mark Kelly, am entirely responsible for the offensive verbiage I spew forth.

Have I offended anyone with this post?  I would not be surprised.

If offended, please whinge to me at the email address above. 

Please leave poor Kevork alone.  It is not his fault.



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