I am doing a simple database design task as a training exercise where I have to come up with a basic schema design for the following case:

I have a parent-child hierarchy of products (example, Raw Material > Work in Progress > End Product).

  • Orders are placed at each level.
  • Number of orders shall be viewable in weekly buckets for the next 6 months.
  • Demand forecast can be done for each product level.
  • Demand forecast for any week within next 6 months can be done today.
  • Demand forecast is done for weekly buckets, for the next 6 months.

Demand Forecast is usually done at the higher level in hierarchy (Raw Material or Work in Progress level) It has to be disaggregated to a lower level (End Product).

There are 2 ways in which demand forecast can be disaggregated from a higher level to lower level:

  1. User specifies percentage distribution for end product. Say, there's a forecast of 1000 for Work In Progress.. and user says I want 40% for End Product 1 and 60% for End Product 2 in bucket 10.. Then for 10th week (Sunday to Saturday) from now, forecast value for End Product 1 would be 400 and, for End Product 2 would be 600.
  2. User says, just disaggregate according to orders placed against end products in Bucket 5, and orders in bucket 5 for End Product 1 and 2 are 200 and 800 respectively, then forecast value for EP1 would be ((200/1000) * 100)% and for EP2 would be ((800/1000) * 100)% of forecast for 'Work in Progress'.

Forecast shall be viewable in weekly buckets for the next 6 months and the ideal format should be:

product name | bucket number | week start date | week end date | forecast value | created_on

PRODUCT_HIERARCHY table could look like this:

id  |   name                |   parent_id
1   |   raw material        |   (null)
2   |   work in progress    |   1
3   |   end product 1       |   2
4   |   end product 2       |   2

ORDERS table might look like this:

id | prod_id | order_date | delivery_date | delivered_date


prod_id is foreign key that references id of PRODUCT_HIERARCHY table,

How to store forecast? What would be a good basic schema for such a requirement?

My idea to select orders for 26 weekly buckets is:

        ADD_MONTHS(sysdate, 6), 
    delivery_date BETWEEN SYSDATE AND ADD_MONTHS(sysdate, 6);

But this will give weekly buckets starting from today irrespective of the day. How can I convert them to Sunday to Saturday weeks in Oracle?

Please help designing this database structure.

(will be using Oracle 11g)

  • 1
    sounds like you're building a data warehouse. order would be the fact table. product and date the dimension tables. You might want to use an accumulating fact table, as you are looking at a process that has several steps. Feb 10, 2013 at 20:25

1 Answer 1


Okay, so here's the data model I came up with.

PRODUCT -- to store product information and maintain parent-child hierarchy

id  NUMBER  "Primary Key Not Null"                  
level_code  VARCHAR2    Not Null                    
name    VARCHAR2    Not Null                    
description VARCHAR2                        
parent_id   NUMBER  Foreign Key references PRODUCT(id)                  

ORDERS -- to store orders for products

id  NUMBER  "Primary Key Not Null"                  
prod_id     NUMBER  "Foreign Key references PRODUCT(id) Not Null"                   
order_type  VARCHAR2    "Not Null Default 'Default'"
order_qty   NUMBER  Not Null
order_date  NUMBER  Foreign Key references DATE_INFO(date_key)
delivery_date   NUMBER  "Foreign Key references DATE_INFO(date_key)
Check delivery_date >= order_date"

FORECAST -- to store forecast value for products (store value for higher levels, store value for lower levels after disaggregation from a parent)

id  NUMBER  "Primary Key Not Null"
product_id  NUMBER  "Foreign Key references PRODUCT(id) Not Null"
forecast_value  NUMBER  Not Null
week    NUMBER  "Foreign Key references DATE_INFO(date_key) Not Null"                   

DISAGGREGATION_RULES -- to store which method was used for disaggregating a value from a higher level to lower level and how much percentage got distributed to lower level

id  NUMBER  "Primary Key Not Null"
parent_product_id   NUMBER  "Foreign Key id references PRODUCT(id) Not Null"
child_product_id    NUMBER  "Foreign Key id references PRODUCT(id) Not Null"
method  VARCHAR2    Not Null                    
from_week   NUMBER  "Foreign Key references DATE_INFO(date_key) Not Null"
to_week NUMBER  "Foreign Key references DATE_INFO(date_key) Not Null Check end_week >= start_week"
percent_distribution    NUMBER  Not Null                    

DATE_INFO -- date dimension, has information about start date (has to be Saturday) and end date corresponding to the week in which a particular date falls

date_key    NUMBER  "Primary Key
Not Null"                   
full_date   DATE    Not Null                    
week_begin_date DATE    Not Null                    
week_end_date   DATE    Not Null

As for the bucket number .. I am calculating week start date (date on Saturday, in my case) with the following function

CREATE OR REPLACE FUNCTION get_week_start_date(v_bucket_num IN NUMBER)
  week_start_date DATE;
  SELECT (TRUNC(SYSDATE+2, 'IW')-2) + ((v_bucket_num-1) * 7)
  INTO week_start_date FROM dual;
  RETURN week_start_date;

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.