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Thread: need Suggestion

  1. #1
    Join Date
    Jul 2011
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    Question Unanswered: need Suggestion

    Hi All,

    could you any one help me what is exactly called as "Whole key". As of my knowledge it is like Under second and third normal forms, a non-key field must provide a fact about the key, us the whole key, and nothing but the key. In addition, the record must satisfy first normal form. But i need exact defination of wht is called Whole key.

    Please help me out ASAP..
    Thank you

  2. #2
    Join Date
    Jan 2007
    Location
    Jena, Germany
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    Can you tell us the context where this term is used? It is not a standard term in the relational model and/or SQL. So the author who used it must have some meaning attached to it, which may become clear from the whole text.
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

  3. #3
    Join Date
    Dec 2007
    Location
    London, UK
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    741
    Quote Originally Posted by rajivjoshi View Post
    Hi All,

    could you any one help me what is exactly called as "Whole key". As of my knowledge it is like Under second and third normal forms, a non-key field must provide a fact about the key, us the whole key, and nothing but the key. In addition, the record must satisfy first normal form. But i need exact defination of wht is called Whole key.

    Please help me out ASAP..
    Thank you
    Whole key just means all the attributes of a key rather than only some proper subset of the attributes of a key (a key can consist of any number of attributes).

    The phrase: "the key, the whole key and nothing but the key" is commonly used as an informal way of describing 2nd and 3rd Normal Forms. 3rd Normal Form requires that every non key attribute depends on every candidate key - meaning the entire set of attributes of every key and not just part of any key. Hence "the whole key".

    Note that a table can have more than one candidate key and therefore the phrase "the key, the whole key and nothing but the key" isn't really sufficient. A more accurate description of 2NF and 3NF would be: "Every non-key attribute must be a fact about every key, the whole of every key and nothing but the keys". Unfortunately that doesn't scan so well!

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