Which ER-model term corresponds to a foreign key in the relational database…
2024
Which ER-model term corresponds to a foreign key in the relational database model?
Answer: C. 1 : 1 (one to one) or 1 : N (one to many) relationship type — CONCEPTER-to-relational mapping converts entity types, attributes, and relationship types into relational structures. Cardinality determines how a…
- A.
Composite attribute
- B.
Entity type
- C.
1 : 1 (one to one) or 1 : N (one to many) relationship type
- D.
M : N (many to many) relationship type
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Correct answer: C
CONCEPT
ER-to-relational mapping converts entity types, attributes, and relationship types into relational structures. Cardinality determines how a relationship is represented: when at least one side has a single matching occurrence, a reference can be stored in a participating relation; when both sides may have many matches, a separate relationship relation is needed.
APPLICATION
The stem asks for the ER-model term represented by a foreign key. A 1:1 or 1:N relationship has a side whose participating occurrence can be identified from the other side, so the relationship can be carried by a foreign key in one participating table.
CONTRAST
A composite attribute is decomposed into its simple component attributes, which become columns.
An entity type maps to a relation that stores its entity instances.
A 1:1 or 1:N relationship type can be implemented by placing a foreign key in one participating relation.
An M:N relationship type normally maps to a separate relationship relation containing keys from both participating relations.
CROSS-CHECK
In a Department–Employee 1:N relationship, each employee belongs to at most one department, so the department key can be stored with the employee row. This independently demonstrates the foreign-key mapping rule.
Therefore, the matching ER-model term is 1:1 or 1:N relationship type.