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Thread: normalisation

  1. #1
    Join Date
    Mar 2008
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    normalisation

    hi

    i have done normalisration for skill report of on company and it contain following attribute and...
    i have attached the pic of it please check it and tell me which pat of it i am wrong?



    pic:
    http://aycu14.webshots.com/image/469...1146708_rs.jpg

    thanks
    Attached Thumbnails Attached Thumbnails normalisation.JPG  

  2. #2
    Join Date
    Apr 2002
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    Toronto, Canada
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    which part is wrong? one or maybe two of them

    Tutor Skills is possibly wrong, depending on how the skills are stored (if it is a decription, it's probably okay, but if it's a list of skills, it's wrong)

    also, you have Dance Description dependent on two key fields, Tutor ID and Dance ID, and that's wrong
    rudy.ca | @rudydotca
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  3. #3
    Join Date
    Mar 2008
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    what i mean by turor skill is that for exmplae:
    tutor skill = 1,2,5
    that mean dance id 1,2 and 5 and then i have description for dance id 1,2 5 the part i get confused is that in first normal form why we take the unique key of tutor and use it as compound key for dance id

  4. #4
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    Mar 2008
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    also, you have Dance Description dependent on two key fields, Tutor ID and Dance ID, and that's wrong

    can u explain a bit more please
    thanks

  5. #5
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    tutor skill = 1,2,5 violates 1NF

    i can explain more if you will give sample rows for { TutorID, DanceID, Dance Description }
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  6. #6
    Join Date
    Mar 2008
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    ok for example imagine this is the list below

    TUtor id Tutor name tutor dob tutor skill dance id dance description
    134 john 21/03/2008 1,3,5 1 salsa
    2 tango
    3 ballay
    that is the example of it but i still dont understand why i should take tutor id as compound key and dance id as primery key for first normal form
    i get confused

  7. #7
    Join Date
    Apr 2002
    Location
    Toronto, Canada
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    20,002
    this --
    Code:
    Tutor id   Tutor name   tutor dob   tutor skill   dance id   dance description
    134        john         21/03/2008     1,3,5      1          salsa
                                                      2          tango
                                                      3          ballay
    has serious problems

    i suggest that you read the chapter in your textbook about normalization again right from the beginning
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

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