ER-Exercise 1A School DatabaseSlide 3Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17ER-Exercise 1Sungchul HongA School Database•A college is divided into several schools.•Each school is administered by a dean.•A dean is a professor•Each school is composed of several departments.–For example, the school of business has an accounting department, a management, marketing, economics, finance, and CIS department.PROFESSORIS DEAN OF►SCHOOLDEPARTMENTOPERATES▼(1..1) (0..1)111M(1..1)(1..*)School has minimum # of deansSchool has maximum # of deansA professor could be a dean of minimum # of schoolsA professor could be a dean of maximum # of schools•Each department offers several courses.DEPARTMENTCOURSEOFFERS►1M(1..1)(1..*)It can have•A course can have many sectionsCOURSESECTIONSHAS►1 M(1..1)(0..*)Sections can have minimum one and maximum one course•Each department has many professors assigned to it. One of those professors chairs the department. Only one of the professors can chair the department to (s)he is assigned, and no professor is required to accept the chair position. Therefore, DEPARTMENT is optional to PROFESSOR in the “chairs” relationship.1 11MIS ASSIGNED TO►Chairs►PROFESSORDEPARTMENT(1..1)(0..1)(1..*)(1..1)•Each professor may teach up to four classes, each one a section of a course. A professor may also be on a research contract and teach no classes at all.PROFESSORCLASSteaches►1M(1..1)(0..4)•A student may enroll in several classes, but (s)he takes each class only once during any given enrollment period.•Each class may have up to 30 students in it.ENROLL►STUDENTSSECTION(8..30)(1..8)How can we enforce the rule that restrict taking same section multiple times in same semester?How can we represent grade?•Each department has several students whose major is offered by that department. However, each student has only a single major and is therefore, associated with a single department.DEPARTMENTSTUDENTenrolls►1 M(1..1)(1..*)•Each student has an advisor in his or her department; each advisor counsels several students. An advisor is also a professor, but not all professors advise students.PROFESSORSTUDENTadvise►1 M(1..1)