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Assignment 1 Question 1.2

Posted by danield 
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Assignment 1 Question 1.2
April 24, 2008 09:11PM
Does anyobody know if the AC_NUMBER field belong to the customer or the company? I cant seem to relate the dependancy to a customer (becuase the same account number is used for 2 different customer surnames) and it doesn't seem to relate to an airplane at all. Don't know if anyone will be able to help. Daniel
Re: Assignment 1 Question 1.2
May 10, 2008 11:41PM
AC_NUMBER is the aircraft number and the primary key of the AIRCRAFT table, and also determines the MODEL_CODE. It is not in the CUSTOMER table, and there should be no COMPANY table.
Re: Assignment 1 Question 1.2
May 26, 2008 01:12PM
How can AC_NUMBER be the primary key - it isn't unique. The primary key should be CHAR_TRIP surely as this is unique and combined with AC_NUMBER you then get your seconday key?
Re: Assignment 1 Question 1.2
May 26, 2008 03:30PM
Well, CHAR_TRIP is unique and the best candidate for being PK, that's how I also see it.

AC_NUMBER does not determine the model code, AC_NUMBER 1234Q and 2256W are for aircraft model-code PA31-350.
Re: Assignment 1 Question 1.2
May 28, 2008 09:34AM
Guys, what awkward_edward said is correct!

You should re-think your table(s) structure if you cant see AC number as the primary key, and yes that does mean it should be unique!

Clue: Remember the table given is not normalised, and contains redundant data.

Btw, does anyone know if 1.1 is supposed to be a question?
Re: Assignment 1 Question 1.2
May 28, 2008 02:12PM
Yah looks like Awkward Edward is right.
1.1 looks like a description/preamble of the problem to me.
Re: Assignment 1 Question 1.2
May 28, 2008 02:53PM
Ok.. I'm still lost...
Re: Assignment 1 Question 1.2
May 28, 2008 03:28PM
Hi...

The AC_Number does refer to the aircraft number. AC_number is not Dependant on the model_code at all as posted previously.

This is how I see it, the model_code refers to something like a cesna. In the table you can see that some of the model_codes are repeating, but the AC_Number for each is different. It is because they are referring to different planes i.e different cesnas. Now, it makes sense by deduction that an aircraft number determines the model_code. Every aircraft has a unique number which the airports use to identify the airplane with. Therefore the model_code only indicates the type of aircraft they are using....

ac_number -> model_code, model..........

If you dont agree, please reply to this thread so we can make a plan. Who figured out the dependacy of the pilot, copilot, flt_engineer and load_master....I said they are all dependent on the char_trip.
Re: Assignment 1 Question 1.2
May 28, 2008 03:42PM
There are two AC_NUMBER's that have the same reference 1234Q and the same MODEL_CODE, and now I think the light bulb has come on as they are on different days and hence the same plane... doh!

Thanks for the clarification... Should be able to finish this question finally...

I also have the pilot, copilot, flt_engineer and load_master dependent on CHAR_TRIP as each flight can have a different pilot as highlighted by Melton being the pilot on two different aircraft models...
Re: Assignment 1 Question 1.2
May 28, 2008 03:49PM
Cool! I agree with char_trip -> pilot, co_pilot etc.... Look at the weight of the cargo carried...the heavier the plane the more crew needed to handle the plane. But there is no indication that the pilot is dependant on the ac_number....like you said Melton is pilot and co-pilot for the same plane.
Re: Assignment 1 Question 1.2
May 28, 2008 04:03PM
This is correct daniel:

Who figured out the dependacy of the pilot, copilot, flt_engineer and load_master....I said they are all dependent on the char_trip.

Cool you guys got it!
Re: Assignment 1 Question 1.2
May 28, 2008 04:05PM
Collaboration at its best guys!!
Re: Assignment 1 Question 1.2
May 28, 2008 04:06PM
char_trip -> pilot, co_pilot,flt_engineer,load_master...I cant see how they can be dependent on anything else
assignments
June 25, 2008 11:06AM
Good discussion. please note: Dear all

With all the admin problems (the website on myUnisa) we had I had decided not to post the 201 yet. I will do so on 15 July. The assignments are with the marker and he will bring it back for capturing. I have a completed suggested solution and will post this.

Regards and have a great time

Prof Sam Lubbe
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