Figure - Relationships

Relationship:  The Data object is connected to one another in a variety of several ways. Consider 2 data objects bookstore and book. Those objects can be represented using the simple notation described. A connection is build among bookstore and book because the 2 objects are associated. But what are the relationships? To conclude the answer we must understand the role of books and bookstores within the circumstance of the software to be established. We can describe a set object relationship pairs which define the relevant relationships.

1. A bookstore orders books
2. A bookstore displays books
3. A bookstore stocks books
4. A bookstore sells books
5. A bookstore returns books

The relationships displays, stocks, orders, sells, and returns described the relevant connections among bookstore and book. In the Figure described 3 object-relationship pairs graphically.

It is important to note which object relationship pairs are bi-directional; which is they can be read in either direction. Books are ordered by a bookstore or the bookstore orders books.