IPA FE Subject A sample Question 22
A question IPA Japan published in 基本情報技術者試験 科目A サンプル問題 問22, translated into English. ITPEC is based on the same exams.
Same question on ITPEC: Apr 2023 Q28
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 the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.