Superclass/Subclass Relationship Types in Logical Data Model

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Questions and Answers

What is the most appropriate option to represent a superclass/subclass relationship in a logical data model?

Creating one relation (correct)

Not representing subclasses

Creating multiple relations

Creating disjoint relationships

In a superclass/subclass relationship, what factors determine the most appropriate representation?

Number of entities involved

Complexity of attributes

Disjointness and participation constraints (correct)

Existence of recursive relationships

For : binary relationship types, what should be posted into a new relation as foreign keys?

Primary key attributes of the entities involved (correct)

Foreign key attributes of the relationship

Attributes of the subclass

Attributes of the superclass

Which type of relationship involves creating a new relation to represent the relationship along with its attributes?

Complex relationship Signup and view all the answers

What forms the primary key of a new relation in : binary relationship types?

Foreign keys and some relationship attributes Signup and view all the answers

In logical data modeling, what is a common approach to represent a superclass entity?

As a parent entity Signup and view all the answers

What is the first step in deriving relations for a logical data model?

Identify the parent entity Signup and view all the answers

How are parent and child entities designated in a one-to-many (1:*) binary relationship?

Parent entity has the foreign key attribute Signup and view all the answers

What is considered when deciding to create relations for a one-to-one (1:1) binary relationship?

Participation Signup and view all the answers

In a 1:1 relationship with mandatory participation on both sides, what approach is taken in creating relations?

Create two separate relations Signup and view all the answers

What does cardinality describe in entity relationship modeling?

Number of possible relationships for each participating entity Signup and view all the answers

How does participation influence relationships in logical data modeling?

'Joins' entities together Signup and view all the answers

In a 1:1 relationship with optional participation on both sides, how is the parent and child entity designated?

Parent and child entities are arbitrarily designated Signup and view all the answers

What are the rules for participation in a 1:1 recursive relationship with mandatory participation on both sides?

Create a single relation with two copies of the primary key; one as primary key and the other as foreign key Signup and view all the answers

Which entity is designated as the parent in a 1:1 Staff Uses Car relationship?

Staff entity Signup and view all the answers

How are attributes in a relationship ordered if there are one or more attributes involved?

Attributes should follow the child's primary key Signup and view all the answers

When designing a 1:1 relationship, what determines the designation of parent and child entities?

Optional participation on both sides Signup and view all the answers

In a 1:1 recursive relationship with only one side having mandatory participation, what can be done?

Create a new relation to represent the relationship Signup and view all the answers

Study Notes

Superclass/Subclass Relationships

The most appropriate option to represent a superclass/subclass relationship in a logical data model is to create a single relation for the superclass and separate relations for each subclass.
Factors that determine the most appropriate representation of a superclass/subclass relationship include the number of subclasses, the complexity of the relationship, and the level of detail required.

Binary Relationships

In : binary relationship types, the foreign keys posted into a new relation are the primary keys of the related entities.
The type of relationship that involves creating a new relation to represent the relationship along with its attributes is a : binary relationship.
The primary key of a new relation in : binary relationship types is formed by combining the primary keys of the related entities.

Logical Data Modeling

A common approach to represent a superclass entity in logical data modeling is to create a single relation for the superclass.
The first step in deriving relations for a logical data model is to identify the entities and their relationships.

One-to-Many (1:*) Relationships

In one-to-many (1:*) binary relationships, the entity on the "one" side is designated as the parent, and the entity on the "many" side is designated as the child.

One-to-One (1:1) Relationships

When deciding to create relations for a one-to-one (1:1) binary relationship, factors such as the complexity of the relationship and the level of detail required are considered.
In a 1:1 relationship with mandatory participation on both sides, the approach taken in creating relations is to combine the primary keys of the related entities into a single primary key.
In a 1:1 relationship with optional participation on both sides, the parent and child entities are designated based on the business rules and requirements.

Cardinality and Participation

Cardinality describes the number of instances of one entity that can be related to the instances of another entity in entity relationship modeling.
Participation influences relationships in logical data modeling by determining the mandatory or optional nature of the relationships.

Recursive Relationships

In a 1:1 recursive relationship with mandatory participation on both sides, the rules for participation require each instance of the entity to be related to exactly one instance of itself.
In a 1:1 Staff Uses Car relationship, the Staff entity is designated as the parent.
When designing a 1:1 relationship, the designation of parent and child entities is determined by the business rules and requirements.

Attribute Ordering

When there are one or more attributes involved in a relationship, the attributes are ordered based on the business rules and requirements.

Miscellaneous

In a 1:1 recursive relationship with only one side having mandatory participation, the mandatory side can be designated as the parent, and the optional side can be designated as the child.

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Description

This quiz covers the process of deriving relations for a logical data model, focusing on superclass/subclass relationship types. Topics include identifying superclass as the parent entity, representing the relationship as one or more relations, and factors affecting the representation choice.