Week 3 : Database Design

Question 1

What is an Entity Relationship Diagram?

Answer 1

An approach that identifies important data, entities and relationships that must be represented in a model.

Question 2

What is Unified Modelling Language?

Answer 2

A diagrammatic notation modeling language that provides a standard way to visualize the design of a system.

Question 3

What is an Entity Type?

Answer 3

A group of objects with the same properties which are identified by the enterprise as having an independent existence.

Question 4

What is a relationship occurance?

Answer 4

A uniquely identifiable association that includes one occurrence from each participating entity type and indicated the particular entity occurrences that are related.

Question 5

What is a semantic net?

Answer 5

An object-level model that uses symbols to represent entities, relationships and examine examples of individual occurrences of the relationships.

Question 6

What are the degrees of a relationship type?

Answer 6

Binary, Ternary and Quaternary.

Question 7

What is a recursive/unary relationship?

Answer 7

A relationship type in which the same entity type participates more than once in different roles.

Question 8

What does a role name do?

Answer 8

These determine the function of each participant or are used when two entities are associated through more than one relationship.

Question 9

What is an attribute domain?

Answer 9

The set of allowable values for attributes. It defines the potential values an attribute may hold.

Question 10

What are the types of attributes?

Answer 10

Simple, composite, single-valued, multiple-valued and derived.

Question 11

What is Multiplicity?

Answer 11

The number of possible occurrences of an entity type that may relate to a single occurrence through a particular relationship and a representation of the policies established by the user.

Question 12

What are the types of Cardinalities?

Answer 12

One to one, one to many and many to many.