Module 6 - Data Modeling Flashcards Preview

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Flashcards in Module 6 - Data Modeling Deck (8)
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1
Q

Logical and Physical data models?

A

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

2
Q

What is an entity relationship diagram (ERD)?

A

A data model that shows the data relationship between entities.

3
Q

What is an ERD entity?

A

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

4
Q

ERD Identifier Types

A

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

5
Q

ERD Relationships

A

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

6
Q

ERD Cardinality

A

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

7
Q

ERD Modality

A

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

8
Q

ERD Building Tips

A

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