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  1. #1
    Join Date
    Nov 2005
    Posts
    2

    Unanswered: Hey everyone Please help with 3NF(Third Normal Form)

    Hi everyone im new to this forum and basically id really appreciate help on third normal form im doing a database assignment in college i dont have much experience with databases, id like every1 who will to look at these tables im using for a database to do with estate agents and tell me what ive got wrong and n e other comments thanks...Also if you wouldnt mind identifying the primary keys i might of left out. The primary keys i have are in bold , thanks ever so much

    PROPERTY
    Property No
    Vendor No
    Date
    Address
    Property Type
    Tenure
    No of Bedrooms
    Bathrooms with shower and or bath
    Kitchen Size
    Kitchen Type
    Living room Size
    Fireplace
    Fireplace Type
    Heating Type
    Garden
    Garden Type
    Garage
    Asking Price

    BUYER
    Buyer No
    Surname
    Forename
    Address
    Postcode
    Tel No
    Solicitor
    Property Type
    Tenure
    Price Range


    VENDOR
    Vendor No
    Property No
    Solicitor No
    Date
    Surname
    Forename
    Address
    Home Tel
    Mobile Tel

    SOLICITOR
    Solicitor No
    Surname
    Forename
    Address
    Phone No

    OFFER
    Property No
    Date
    Buyer No
    Offer

  2. #2
    Join Date
    Mar 2003
    Location
    The Bottom of The Barrel
    Posts
    6,102
    Provided Answers: 1
    You're missing a bunch of tables. anything suffixed with "Type" in your Property table should most likely be referencing another table. Also, don't use spaces in your field names, trust me on this.

    Why is Property No in the vendor table? Will each vendor only have one property? If so, why is Vendor No in the Property table?

    What's the solicitor supposed to track? I don't know real estate...

    In your offer table, you're using property no as the primary AND foriegn keys. Wht happens if you get more than one offer on the same property?
    oh yeah... documentation... I have heard of that.

    *** What Do You Want In The MS Access Forum? ***

  3. #3
    Join Date
    Dec 2003
    Posts
    268

    A shot

    Here is my half-assed effort at normalization of the data you gave. Without knowing the requirements I can only speculate...

    This is not 100% complete (to be read, don't turn this in, but look at it and understand what is being done)

    if you want to achieve 3NF then there some things to condsider

    - Store the addresses in one field and reference them from thier respective table, i.e. a person may be a vendor, seller or buyer at some point in time in the proces
    - store the room information as a weak entity from room type. This can provide you room counts etc. any derived value should not be stored in a DB.
    - make sure there are tables to store all 'type' references

    I have included an ER and the SQL for table generation etc. This is not 100% correct, and data validation wasn't even considered (allow of nulls etc) but again, just look at it.

    Hope this helps.
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