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#1 dariusd7  Icon User is offline

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ERD Help

Posted 23 October 2013 - 10:12 AM

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
Property
PK Prop_id
address
city
state
zip


entity
Status
PK_Status_id
for_sale
sold
Contract
For_rent
Leased


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

I can't attach Visio files..or word file to show you what I came up with., but I know its wrong.

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