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Question

Hello All,
I am using Oracle 11g R2 SOE.
What is the best practice for Real Estate Data Model ?
This one :
http://www.databaseanswers.org/data_models/real_estate_properties/index.htm
Or
As I got, In this thread {thread:id=2521579} I was advised to store the details of Properties in one Table, and create views on that table for each Category (Apartment, Plot , Office ..)
CREATE TABLE UNIT
    ID           NUMBER (5) NOT NULL ,
    BUILDING_ID  NUMBER (3) NOT NULL ,
    UNIT_NO      VARCHAR2 (10 BYTE) NOT NULL ,
    CAT_ID       NUMBER (2) NOT NULL , -- Apartment , Office ... Plot
    OWNER_ID     NUMBER (5) NOT NULL ,
    UNIT_SIZE    NUMBER (6) NOT NULL ,
    UNIT_VIEW    NUMBER (3) NOT NULL ,
    LISTED_BY    NUMBER (2) NOT NULL ,
    IS_EXCLUSIVE VARCHAR2 (1 BYTE) DEFAULT 'N' ,
    KEY_STATUS   NUMBER (2) ,
    VIDEO        VARCHAR2 (11 BYTE) ,
    NOTE        VARCHAR2 (300 BYTE) ,
    CREATED      TIMESTAMP ,
    CREATED_BY   VARCHAR2 (15 BYTE) ,
    UPDATED      TIMESTAMP ,
    UPDATED_BY   VARCHAR2 (15 BYTE)
ALTER TABLE UNIT ADD CONSTRAINT UNIT_PK PRIMARY KEY
  ID
ALTER TABLE UNIT ADD CONSTRAINT UNIT_UN UNIQUE
  BUILDING_ID , UNIT_NO
;The question is about CAT_ID. The Categories Lookup table contains these values:
Apartment.
Office.
Retail.
Plot.
Full Building.
Warehouse
Villa
The main difference between Apartment/Office and Plot / Full building are:
The attributes of Apartment / Office are  :
Beds  ( When Office, it is beds is 0)  , Balcony_number  , parking
The attributes of Plot / Full building are   :
Height , Built up area , Use_id  (Plot use could be Residential or commercial or mixed )So, shall I add these 6 columns to the UNITES Table and create views on it ??? Or I should go with the aforementioned model in databaseanswers.org ?
** I use ORACLE APEX..
Regards,
Fateh
Edited by: Fateh on May 2, 2013 7:58 PM

Answer 1

Fateh wrote:
The question now, is it fine for those categories if they share the same columns where the values have different meaning based on the Category ? Namely,
the column Beds may have these values:
If it is Office then 0
If it is Apartment then 1 - 8
If it is Plot then 10 - 120
You're talking about a single attribute that has different meanings based on the value of another attribute, in another relation. That does not make logical sense to me, and I wouldn't ever do that. Those values would be rendered meaningless if the category you use to derive their meanings is deleted.