4. Again consider the domain model class diagram shown in Figure 4-16. Add the following to the diagram and list any assumptions you had to make: A faculty member usually teaches many course sections, but some semesters, a faculty member may not teach any. Each course section must have at least one faculty member teaching it, but sometimes, faculty teams teach course sections. Furthermore, to make sure that all course sections are similar, one faculty member is assigned as course coordinator to oversee the course, and each faculty member can be the coordinator of many courses.

Figure 4-16

106 PART 2 Systems Analysis Activities A refined university coutse etrolment domain mode cuss dugram with an assooiaton CouraeEnrollme grade Studert udontiD oom Number FIGURE 4-17 An initial band booking dormein model class diagram with a mary-to-many bandNarre yearsirBand 1., style starlTime Another example of a domain model class diagram with a many to-many association is shown in Figure 4-17. A band has one or more band memhers, and in this case a band member is in one and only one band. The many-to-many association is between the classes Band and Concert, A band is booked for zero or more concerts, and a concert books one or more bands. Note that on the minimum multiplicities, a band migh: not have any concerts hooked at a given time, but a concert is ardinarily created only when at least one band is hooked. These minimum multiplicities can seem somewhat arbitrary, although they do convey important information for programmers and database analysts, Be sure t is the policymakers who make the decisions about multiplicity constraints, Looking more closely at the many to-many association, the analyst might ask if there is some additional information about the booking that needs to be captured and remembered by the system. Is it important to store the base pay expected for the booking Pay differs for each concert. Is it important to store the order of performances at the concert? Some booking mightbe main act and some might be opening act. Figure 4-18 shows a refined domain model class diagram