I'm confusing myself a lot here. I did this before however have never got the hang of it. So I really need help, main issue is 2nf I just get the dependencies completely wrong. So I am practising ready for next year really. So yes this would be classed as homework.

Here is the original document I have to preform normalization on.

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The form is link no1

My attempts are no2 and no3

So, basically. Where am I going wrong? Why am I going wrong? Can you explain how to get back on track without doing it obviously. I know it's shocking, but I never understood all this :/ fine with sql but this side of things, not a chance.

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Here is another attempt, what one is close and why?

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  • 1
    You should consider the relationships between individual columns. For example, what is the relationship between film titles and film references? Similarly, what is the relationship between a category and a category type? Also, think about what would happen to these various fields if a film appeared on two separate orders. – Joel Brown Aug 9 '12 at 16:11
  • @JoelBrown thats one of the things I'm unsure on. Am I doing this in the consideration of many order forms or just this one? So would I have to consider the scenario of the same films on other orders? So for tiles and references would it be the film cant exist without the reference? – Kyle93 Aug 9 '12 at 16:21
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    Kyle, you should always think in terms of your tables having many records. When you model data you often think about single instances of things, but if you only had one of something in real life, you probably wouldn't need a database table to keep track of it. One good "trick" to use is to start by assuming that every tangible thing you are keeping data on will need its own table. If you presume a table and then find it doesn't have any/many attributes then you can scrap the idea or think about rolling the attribute or two into another table. – Joel Brown Aug 9 '12 at 20:57
  • Your second model is much better. Supplier, Film and Category belong as full fledged entities because they are real things with their own attributes and they will be referenced by many orders. Your diagram has the crow's feet backwards on Item/Film and Item/Category. Your FK columns are in the Item table, which is right. The side with the FK column is the side that gets the crow's foot. – Joel Brown Aug 9 '12 at 21:01
  • @JoelBrown Yeah that makes sense. Also, thanks thats a really nice idea, should really help a lot! As for 2nd comment. Thats good news. I will sort them out in the morning and update this and I was not sure what way they went so thanks for clarifying. Lastly, how far is my 2nd attempt from being correct? What part of it is wrong and any handy hints? :) Thanks a lot tho! Really helpful – Kyle93 Aug 9 '12 at 21:06

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