ITPEC FE Morning April 2023 Question 28
Which of the following is the appropriate interpretation of the conceptual data model shown in the diagram in UML?
Explanation
An employee can belong to several departments at once — the multiplicity 1. beside Department says each employee belongs to one or more departments.
A multiplicity is written at the far end of an association: it states how many objects of that class one object at the other end is linked to.
- •
1.at the Department end: one employee belongs to at least one and possibly many departments..* - •
0.at the Employee end: one department has zero or more employees..*
Answer (b)
Why not others:
- •(a) —
0.beside Employee allows a department with no employees..* - •(c) — the lower bound 1 in
1.beside Department requires every employee to belong to at least one department..* - •(d) — multiplicities limit how many objects each object is linked to; they say nothing about the total numbers of employees and departments being equal.
Key rule: The multiplicity next to a class tells how many instances of that class one instance on the other side is linked to; a lower bound of 0 means optional, 1 means mandatory.
Databases · AI-written, may contain errors
This question comes from an official ITPEC past paper. ITPEC Practice is an independent study tool and is not affiliated with ITPEC. See the official FE past-paper collection or Report an issue.