From the course text: Chapter 2, Problems and Exercises #2-39 parts c and e, and #2-43) ;

 

c. A college course may have one or more scheduled sections or may not have a scheduled section. Attributes of COURSE include Course ID, Course Name, and Units. Attributes of SECTION include section Number and Semester ID. Semester ID is composed of two parts: Semester and Year. Section number is an integer (such as 1 or 2) that distinguishes one section from another for the same course but does not uniquely identify a section. How did you model SECTION? Why did you choose this way versus alternative ways to model SECTION?

 

 

 

 

e. The loan office in a bank receives from various parties requests to investigate the credit status of a customer. Each credit request is identified by a Request ID and is described by a Request Date and Requesting Party Name. The loan office also received results of credit checks. A credit check is identified by a Credit Check ID and is described by the Credit Check Date and the Credit Rating. The loan office matches credit requests with credit check results. A credit request may be recorded before its result arrives; a particular credit result may be used in support of several credit requests. Draw an ERD for this situation. Now, assume that credit results may not be reused for multiple credit requests. Redraw the ERD for this new situation using two entity types, and then redraw it again using one entity type. Which of these two versions do you prefer, and why?

 

 

 

 

 

 

2-43. In the chapter, when describing Figure 2-4a, it was argued that the Received and Summarizes relationships and TREASURER entity were not necessary. Within the context of this explanation, this is true. Now, consider a slightly different situation. Suppose it is necessary, for compliance purposes (e.g., Sarbanes-Oxley compliance), to know when each expense report was produced and which officers (not just the treasurer) received each expense report and when each signed off on that report. Redraw figure 2-4a, now including any attributes and relationships required for this revised situation.