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  1. #1
    SitePoint Addict coolbuzz's Avatar
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    Normalization,Decomposition........?

    I have the book of 'Database System Concepts' by Korth.
    From that book I am unable to understand various topics such as 1 to 4 normal forms,functional dependency,canonical cover,Boyce-Codd Normal form,decomposition
    I have read about the normalisation thread in this forum but cannot get the concepts properly from those sites.
    Can anyone please point to good resources where I can get a proper understanding of the above mentioned topics because as I advanced further in the book these concepts(espcially normal forms) seems to appear many times?

  2. #2
    Sultan of Ping jofa's Avatar
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    Well, the concept normalization (or the purpose) isn't difficult to understand, but the terms associated with it is a pain.
    Fortunately, in real life you don't have to be that formal, it's mostly common sense
    Only one value in each row/column, no repeated values etc
    Anyway, I will try to "translate"...
    Functional dependency: just like in mathematics, when y = f(x), one attribute/column of a relation/table can depend on another attribute/column, for example "employee_id" always gives you one specific value for the attribute "position"
    Decomposition = when you split one relation/table into two or more separate relations/tables
    Canonical cover = Think I have to find my old db systems book to answer that one... I guess the meaning is = the process of reducing number of functional dependencies - if you have A⇒BC, then A⇒B is not "needed" because it's already covered by A⇒BC
    (Maybe someone can correct me?)

    The normal forms; here's a summary (in the section "Informal Overview")
    http://www.wikipedia.org/wiki/Database_normalization

  3. #3
    SitePoint Addict coolbuzz's Avatar
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    Thanks jofa for the reply.
    The problem is that even if I skip those sections they keep on appearing in some or the other topic due to which I am unable to understand certain things so I decided to first complete these and then head further.
    Uptil now,I have understood only the 1,2 NF and nothing else.
    Am awaiting for more replies and trying my best to get the info from other sources.

  4. #4
    Sultan of Ping jofa's Avatar
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    Congratulations to you, if you understood the 2NF (I never did, think 1NF and 3NF are easy, but I could never comprehend the 2NF)

    I know there are grizzled db veterans in this forum that sooner or later will give you a better answer than my attemp above

    Meanwhile, I will repeat the section about "canonical cover", that I obviously missed the first time I read the book...

  5. #5
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    there are some links to resources on the web for database normalization here --

    http://r937.com/links.cfm?links=sql

    rudy


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