Exam (elaborations)
Comm 226 Assignment 2 ( got 90+) Concordia University
- Course
- Institution
Comm 226 Assignment 2 ( got 90+) Concordia University
[Show more]
1 review
By: davidchorna • 4 weeks ago
Seller
Follow
smartzone
Reviews received
Content preview
Comm 226 Assignment 2 ( got 90+) Concordia University1) Draw the ERD of the database that could be used to support the operations of the business
described in the case (3 marks). The ERD should identify:
• Primary keys and Foreign keys;
• Entities and Attributes;
• Relationships and Cardinalities (e.g. one-to-one, one-to-many).
Next to the ERD in your submission, list the assumptions made when designing the ERD. If an element of
the business case does not provide the information necessary to know for certain whether one design
choice should be made over another, the choice you make will be accepted if it correctly reflects your
assumptions.
SOLUTION TO Q1)
Assumptions:
The relationships are as follows:
1) A book can have been written by many authors and one author can have written many books:
many to many relationships.
2) A customer can buy as many books as they want.
3) Books can be published by only one publisher, but a publisher can publish many books: one to
many relationship
4) A customer can have many orders but only one order can attribute to a single customer: many
to one relationship
5) An order can have multiple books and a book can be part of multiple orders: many to many
relationship
- You cannot have many to many relationships, so transition tables were created to show many
to many relationships between “Book, Author” and “Order and Book” relationship
Assumptions of primary key:
1) Unique
2) Never changing/can’t be repeated
3) Never null
Foreign keys assumptions:
1) Doesn’t have to be unique
2) They can be repeated
3) Multiple foreign keys in one entity
Assumptions on cardinalities (based on what it takes (the minimum) to be in the system or bookstore):
Book and author:
- A book has to be written by a minimum of 1 author (one or many)
- Minimum number of books an author can write is 1 (one or many)
Customer and Books:
- A customer can buy one or more books (one or many)
Book and publisher:
- A book can be published by a minimum of 1 publisher (one or many)
, - Minimum amount of books published by a publisher to be in the book store is 1 (one or many)
Customer and order:
- A customer can exist in the system but a customer can have 0 orders (zero or many)
- Minimum of 1 order attributed to a customer (an order can have only 1 customer and not many)
– one (and only one)
Order and book:
- An order has to have a minimum of 1 book (one or many)
- A book can be a part of 1 or more orders (one or many)
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller smartzone. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $10.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
67096 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now