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  1. #1
    Join Date
    Oct 2012
    Posts
    9

    Is Address a key candidate?

    I wonder if address is a key candidate. Need that for 2nd NF

  2. #2
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    naw, man, too much opportunity for inadvertent duplication of key values with minor misspellings
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  3. #3
    Join Date
    Oct 2012
    Posts
    9
    Okay but if i have a Relation like this:
    Person:=PID, FirstName, LastName, Address
    but a person can have more than just one address (attachment)


    Against which NF is this relation and why?
    Attached Thumbnails Attached Thumbnails address.jpg  

  4. #4
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    it isn't against any normal form, because presumably PID is the primary key, so therefore that model cannot have more than one address per person
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  5. #5
    Join Date
    Oct 2012
    Posts
    9
    Okay, thanks.

  6. #6
    Join Date
    Jun 2003
    Location
    Ohio
    Posts
    12,592
    Address could be a key candidate for a table of buildings or intersections, but not for individuals.
    If it's not practically useful, then it's practically useless.

    blindman
    www.chess.com: "sqlblindman"
    www.LobsterShot.blogspot.com

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