Consider an organization with which you frequently interact, such as a bank, credit card company, university, or insurance company, from which you receive several computer-generated messages, such as monthly statements, transaction slips, and so forth. Depict the data included in each message you receive from the organization as its own user view; use the notation of Figure l-3a to represent these views. Now, combine all of these user views together into one conceptual data model, also using the notation of Figure l-3a. What did you observe about the process of combining the different user views? Were there inconsistencies across the user views? Once you have created the conceptual data model, would you like to change anything about any of the user views?
In Figure 1-3a

CUSTOMER Places Is Placed By ORDER Contains A Is Contained In PRODUCT