Module 6 - Data Modeling

Question 1

Logical and Physical data models?

Answer 1

Logical: conceptual, doesn’t indicate how data is stored, created, or manipulated

Physical: shows how data will actually be stored in the database, created, and manipulated

Question 2

What is an entity relationship diagram (ERD)?

Answer 2

A data model that shows the data relationship between entities.

Question 3

What is an ERD entity?

Answer 3

A person, place, event, or thing in which data is collected

Question 4

ERD Identifier Types

Answer 4

Can be independent or dependent from another entity. An identifier is a unique attribute/ID

Question 5

ERD Relationships

Answer 5

Entities have parent-child relationships, the relationship goes both ways

Question 6

ERD Cardinality

Answer 6

The number of instances of one entity that can be related to another
(1:1)
(1:M)
(M:N)

Question 7

ERD Modality

Answer 7

0: Not required
|: There must be at least one instance of the entity

Question 8

ERD Building Tips

Answer 8

Data stores of DFDs correspond to entities
Only include entities with more than one instance
Do not include entities associated with implementation of system
Entity name = noun
Entity relationship = verb
Attributes of the entity should be relevant to the system
You can turn an M:N into two 1:Ns by adding an intermediate entity