1Introduced by Chen in 1976, what is the ERD considered to be?
A widely accepted graphical tool for data modeling
2What components are depicted in an ERD?
Entities, Attributes, Relationships
3How is an entity represented in an ERD?
By a rectangle containing the entity’s name
4How are attributes represented in the Chen model?
As ovals connected to the entity
5How are attributes represented in the Crow’s Foot model?
In an attribute box below the entity rectangle
6What is a simple attribute?
An attribute that cannot be subdivided
7What is a composite attribute?
An attribute that can be subdivided
8What is a single-valued attribute?
An attribute that can have only one value
9What is a multivalued attribute?
An attribute that can have multiple values and requires a new table to store them
10What is a derived attribute?
An attribute whose value can be calculated from other attributes
11What does connectivity describe?
The relationship classification (1:1, 1:M, M:N)
12What does cardinality express?
The minimum and maximum number of entity occurrences allowed, defined by business rules
13What conditions define a weak entity?
It is existence-dependent and its primary key is partially or totally derived from the parent entity
14What is optional participation in a relationship?
An entity occurrence does not require a corresponding occurrence in the related entity
15What is mandatory participation?
An entity occurrence requires a corresponding occurrence in the related entity
16What is a unary or recursive relationship?
A relationship within a single entity set
17What is a binary relationship?
A relationship between two entities
18What is a ternary relationship?
A relationship involving three entities
19What is a quaternary relationship?
A relationship involving four entities