What is a business rule, and what is its purpose in data modeling?
6. Consider the scenario described by the statement “A customer can make many payments, but each payment is made by only one customer”. Use this scenario as the basis for an entity relationship diagram (ERD) representation.
12. Give an example of each of the three types of relationships.
Use the contents of Figure 2.1 to work problems 1-3.
FIGURE 2.1 Linking Relational Tables
1. Write the business rule(s) that governs the relationship between AGENT and CUSTOMER.
7. Create the basic Crow’s Foot ERD for Tiny College shown above.
9. Typically, a hospital patient recieves medications that have been ordered by a particular doctor. Because the patient often receives several medications per day, there is a 1:M relationship between PATIENT and ORDER. Similarly, each order can include several medications, creating a 1:M relationship between ORDER and MEDICATION.
a. Identify the business rules for PATIENT, ORDER, and MEDICATION.
b. Create a Crow’s Foot ERD that depicts a relational database model to capture these business rules.
16. Create a Crow’s Foot ERD for each of the following descriptions. (Note: The word many merely means “more than one” in the database modeling environment.)
a. Each of the MegaCo Corporation’s divisions is composed of many departments. Each of those departments has many employees assigned to it, but each employee works for only one department. Each department is managed by one employee, and each of those managers can manage only one department at a time.
b. During some period of time, a customer can rent many videotapes from the BigVid store. Each of the BigVid’s videotapes can be rented to many customers during that period of time.
c. An airliner can be assigned to fly many flights, but each flight is flown by only one airliner.
d. The KwikTite Corporation operates many factories. Each factory is located in a region. Each region can be “home” to many of KwikTite’s factories. Each factory employs many employees, but each of those employees is employed by only one factory.
e. An employee may have earned many degrees, and each degree may have been earned by many employees.