Let S be the specification: "Instructors teach courses. Students register for courses. Courses are allocated classrooms. Instructors guide students." Which one of the following ER diagrams CORRECTLY represents S?
A.
(i)
B.
(ii)
C.
(iii)
D.
(iv)
Solution:
Let's break down the given statement into small parts:
- Instructors teach courses.
- Students register for courses.
- Courses are allocated classrooms.
- Instructors guide students.
Possible Entites are Instructor, Course, Student and Classroom.
Possible Relationships are Teaches, Registration, Allocation and Guides.
Option (i): Incorrect because it is showing Student as a relationship but it should be an entity.
Option (ii): Incorrect because it doesn't have a Student entity in ERD.
Option (iii): Incorrect because it doesn't define any relationship between Course and Classroom.
Option (iv): Correct, because it follows all the conditions given.