Week 1

Question 1

What are the three components of the design process?

Answer 1

Conceptual Design, Logical Design, Physical Design

Question 2

What is conceptual design concerned with?

Answer 2

Providing a detailed overview of the enterprise and producing an ER model to illustrate entities, relationships, attributes and constraints on entities

Question 3

What is logical design concerned with?

Answer 3

Mapping the high level conceptual scheme onto the implementation data model that will be used by the database system (relational data model)

Question 4

What is physical design concerned with?

Answer 4

Specifying the physical features of a database, including file organization and choice of index structures

Question 5

What is an entity/entity set?

Answer 5

An entity is a thing or object in the real world that is distinguishable from all other objects.

Question 6

What is a derived attribute?

Answer 6

An attribute such that the value of that attribute can be derived from values of other related attributes or entities

Question 7

What three main things are illustrated in an ER diagram?

Answer 7

Entity, Relationships, Attributes

Question 8

What is an entity set?

Answer 8

An entity set is a collection of entities that share the same properties and attributes.

Question 9

What is an attribute?

Answer 9

Descriptive properties possessed by each member of an entity set

Question 10

What is a relationship?

Answer 10

Association among several entities

Question 11

What is a relationship set?

Answer 11

Set of relationships (associations among several entities) of the same type

Question 12

What are the two ways to participate in a relationship[?

Answer 12

Total or partial

Question 13

What is a cardinality of a relationship set?

Answer 13

MAXIMUM number of times an entity can be associated with a relationship set

Question 14

What are the three cardinalities of relationships?

Answer 14

One to one, One to Many, Many to One

Question 15

Describe a one to many relationship

Answer 15

An entity in A is associated with any number of entities in B

Question 16

Describe a many to one relationship

Answer 16

An entity in A is associated with at most one entity in B, however an entity in B can be associated with any number of entities in A

Question 17

What does the set of candidate keys represent?

Answer 17

All the attributes that could be used to uniquely identify the entity

Question 18

What is a superkey?

Answer 18

The union of all the primary keys of entities within a relationship set

Question 19

What is the primary key of a relationship set?

Answer 19

Union of the primary keys of those participating entity sets that do not have an incoming arrow from the relationship set R

Question 20

What is the participation of a relationship set?

Answer 20

Minimum number of times an entity can be associated with a relationship set

Question 21

What is a weak entity set?

Answer 21

An entity set that doesn’t have sufficient attributes to be able to form a primary key, can’t be uniquely identified without referring to another relationship/entity set

Question 22

What is aggregation?

Answer 22

The abstraction in which relationship sets are treated as higher level entity sets which can participate in relationships

Question 23

What is a discriminator?

Answer 23

The identifying attributes in a weak entity sets that when paired with the identifying relationship/entity set can be used to uniquely identify entities in a weak entity set