Data Mgmt-MIS 372 Ch 2 Qs

Q2.9 What is a multivalued attribute?

An entity attribute for which instances of an entity can have multiple values (things) for the same attribute

Q2.13 What is a binary relationship?

A relationship between two entities

Q2.17 What is a ternary relationship?

A relationship of degree 3, involving three entities

Q2.16 What is an associative entity?

An ER diagram construct used as an alternative way of depicting M:N relationships

Q2.2 What are the basic ER modeling constructs?

Entities and relationships

Q2.5 What are the four possible cardinality constraints?

One, Many, Optional, Mandatory

Q2.6 What are the three types of relationships (maximum cardinality-wise)?

One-to-one, One-to-many, Many-to-many

Q2.4 What is depicted by cardinality constraints?

The cardinality constraints depict the description of the relationship between entities

Q2.1 What is the purpose of ER modeling?

The purpose of ER modeling is to enable the structuring and organizing of the collection requirements process and provide a way to graphically represent the requirements.

Q2.12 How are exact minimum and maximum cardinalities depicted in a relationship?

They are depicted as pairs of numbers in parentheses placed on the relationship lines (minimum, maximum)

Q2.8 What are candidate keys?

When an entity has more than one unique attribute, each unique attribute is also called a candidate key

Q2.15 What is a weak entity?

a construct in an ER diagram used to depict entities that do not have a unique attribute of their own

Q2.7 What is a composite attribute?

an attribute that is composed of several attributes

Q2.11 What is an optional attribute?

an attribute that may be allowed to not have a value

Q2.3 What is a unique attribute?

an attribute whose value is different for each entity instance

Q2.10 What is a derived attribute?

an attribute whose value will not be permanently stored in a database

Q2.14 What is a unary relationship?

an entity that is involved in a relationship with itself