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VCE Stuff => VCE Technology => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Computing: Data Analytics => Topic started by: kempa on October 28, 2009, 05:33:13 pm

Title: Relationships
Post by: kempa on October 28, 2009, 05:33:13 pm

I am having a very hard time getting my head around the relationship diagrams and how to successfully put the infinity of 1 sign in the correct place.
any help please?  :)

Title: Re: Relationships
Post by: ell on October 28, 2009, 07:24:18 pm

Could you give us a sample question that you're stuck on?

Title: Re: Relationships
Post by: kempa on October 29, 2009, 11:41:06 am

Quote from: ell on October 28, 2009, 07:24:18 pm

Could you give us a sample question that you're stuck on?

VCE past exam 2007 question 20

Title: Re: Relationships
Post by: ell on October 29, 2009, 05:06:42 pm

The first thing you should do is ensure that you have a clear idea of what each table/object is and its purpose (if you want you can just scroll down to the bottom for the short answer).

E.g. referring to Q20 MC in VCAA '07, we have three tables: Books, Loans and Borrowers.

Each record in the Books table has details about a particular book - title, author, etc. (obvious).
Each record in the Borrowers table has details about a particular person who borrows - name, phone number (also obvious).

The Loans table is slightly trickier. This is what I think most students are confused by - what exactly are 'Loans'?

If you look at the table, Loans has details about a particular book and a particular borrower. Each record in the Loans table is an instance of when someone has borrowed a book.

The short answer:
How many times can a single book be loaned? A lot - so we say one book can be loaned many times.
How many times can a person make a loan? A lot - so we say one borrower can make many loans.

Title: Re: Relationships
Post by: kempa on October 30, 2009, 07:55:18 pm

Quote from: ell on October 29, 2009, 05:06:42 pm

The first thing you should do is ensure that you have a clear idea of what each table/object is and its purpose (if you want you can just scroll down to the bottom for the short answer).

E.g. referring to Q20 MC in VCAA '07, we have three tables: Books, Loans and Borrowers.

Each record in the Books table has details about a particular book - title, author, etc. (obvious).
Each record in the Borrowers table has details about a particular person who borrows - name, phone number (also obvious).

The Loans table is slightly trickier. This is what I think most students are confused by - what exactly are 'Loans'?

If you look at the table, Loans has details about a particular book and a particular borrower. Each record in the Loans table is an instance of when someone has borrowed a book.

The short answer:
How many times can a single book be loaned? A lot - so we say one book can be loaned many times.
How many times can a person make a loan? A lot - so we say one borrower can make many loans.

I thank you so much!