Database Systems 6th Edition by Ramez Elmasri, Shamkant B. Navathe

تمرين 5

Figure 7.32
-Consider the ER diagram in Figure 7.32. Assume that a course may or may not use a textbook, but that a text by definition is a book that is used in some course. A course may not use more than five books. Instructors teach from two to four courses. Supply (min, max) constraints on this diagram. State clearly any additional assumptions you make. If we add the relationship ADOPTS between INSTRUCTOR and TEXT, what (min, max) constraints would you put on it? Why?