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  1. #1
    Join Date
    Oct 2013

    ERD Help for project..

    I have to build a database for a realty company. However I cannot figure out how to reflect the following buisness rule.

    A Property can only have one status.
    There are multiple Statuses that are available for a Preperty. (Some should be sold, under contract, available for sale, available for rent, Leased)
    I have to create an ERD in Visio and then create the database in Oracle. I pretty much figured out all other buisness rules but this one is confusing me.
    I have to somehow make sure that in the database the preperty can only have ond of the status at any one time. How do i do this, how do i make sure it has only one of the statuses, and keep in mind everything has to be in third normal form.

    entity entity
    Property Status
    PK Prop_id PK_Status_id
    address for_sale
    city sold
    state Contract
    zip For_rent

    I don't think this is right. How do i insure that only field is select and that you cant have a preprty showing as both sold or under contract, or for rent and leased. I thought I should make two entities one for property being sold, and another for property being leased, but I still can't figure how to make sure only one field is selected...please help

    file attached showing what I came up with.. Help!!!!
    Attached Files Attached Files

  2. #2
    Join Date
    Jul 2012

    You will find some Data Models relating to Real Estate on my Database Answers Web Site :-


    Barry in London

  3. #3
    Join Date
    Nov 2013
    Damn, nice site!!!

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