I am trying to understand and make use of Tutorial: Data Modeling for a Small Database
During this tutorial I'm supposed to make Transactions Entity containing two attributes that will refer to Patrons (patron_id) and Books Entities (book_id) (2.1.4)
Later, I'm adding two one-to-many relations that duplicate mentioned attributes in Transactions Entity (patron_id1 and book_id1). (2.1.5)
So here comes my questions: what's the purpose of creating those attributes in point 2.1.4 if they're then duplicated in paragraph 2.1.5?
If it might be crucial, i'm using Oracle SQL Developer Data Modeler Version 184.108.40.2065 Build 825 on jdk1.7.0_25.
Bonus question: How to turn on attributes types on Logical Diagram? I can't find corresponding option anywhere...
I would be really grateful for every answer and for every trick!