Question at position 49 In an ERD, cardinality specifiesThe range of allowable values for an attributeThe unique identifier for an entityThe minimum and maximum number of instances of one entity that can be associated with instances of another entityThe number of attributes within an entity

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BlackTom AI · Accepted Answer

First, let's restate the question and options to ensure clarity: In an ERD, cardinality specifies which of the following: options A through D.

Option A: 'The range of allowable values for an attribute' — This describes the domain or domain constraints of a single attribute, not the relationship between two entities. Cardinality is about how many instances of one entity can be associated with instances of another entity, not about the values an attribute may take.

Option B: 'The unique identifier for an entity' — This refers to the entity's primary key or unique key. Cardinality does not define identifiers; it concerns the numerical relationship in associations between entities.

Option C: 'The minimum and maximum number of instances of one entity that can be associated with instances of another entity' — This precisely matches the concept of cardinality in ER diagrams, which expresses how many related instances can participate in a relationship (e.g., one-to-one, one-to-many, many-to-many) and the bounds of participation.

Option D: 'The number of attributes within an entity' — This concerns the entity's attribute count or schema width, not the inter-entity participation constraints. Cardinality does not specify how many attributes an entity has.

Now, analyzing the options collectively:
- A misinterprets cardinality as attribute value ranges, which is actually about domains, not relationships between entities.
- B confuses cardinality with key designation; keys determine identity, not participation in relationships.
- D confuses cardinality with attribute cardinality within an entity; that is about attributes, not the relationships between entities.
- C correctly identifies cardinality as the specification of minimum and maximum participation counts between two related entities, which is the core meaning of cardinality in ER diagrams.

In summary, understanding cardinality as the bounds on how many instances of one entity can be linked to instances of another entity aligns with standard ER modeling concepts, whereas the other options describe related but distinct ideas (attribute domains, keys, and attribute counts).

Question at position 49 In an ERD, cardinality specifiesThe range of allowable values for an attributeThe unique identifier for an entityThe minimum and maximum number of instances of one entity that can be associated with instances of another entityThe number of attributes within an entity

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Question at position 49 In an ERD, cardinality specifiesThe range of allowable values for an attributeThe unique identifier for an entityThe minimum and maximum number of instances of one entity that can be associated with instances of another entityThe number of attributes within an entity

查看解析

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类似问题

In an ER diagram, the weak entity is typically depicted with a _________ ___________, and the relationship between the weak entity and the strong entity is shown with a __________ ___________.

In the following diagram, which of the answers below is true?

Identify the minimum cardinality of any E-R Diagram relationship:

In an ER-Diagram, relationship cardinality is represented as a:

in ERDplus a label:

A pair of perpendicular (crossing) lines across a relationship line, next to an entity, indicates that:

Observe the ER Diagram for the ABC Retailer: Which of the following is true according to the ABC Retailer ER diagram?

Question at position 16 What does a "relationship" in an ERD represent?A specific attribute within an entityThe primary attribute of an entityAn association between two or more entitiesThe unique identifier of an entity

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希望你的学习变得更简单

In an ER diagram, the weak entity is typically depicted with a ___ _, and the relationship between the weak entity and the strong entity is shown with a _____.