Database Fundamentals 2 Flashcards

1
Q

What is a model?

A

An abstraction of a real-world object or event.

It is useful in understanding the complexities of the real world environment.

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2
Q

What is a data model?

A

Relatively simple representation of complex real-world data structure.

It is often graphical.

It is an abstraction - One cannot draw the required data out of the data model.

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3
Q

Data Model Basic Building Blocks (4)

A
  1. Entity: anything about which data are to be collected and stored.
  2. Attribute: A characteristic of an entity.
  3. Relationship: Describes an association among entities.
    - One to many (1:M)
    - Many to many (M:M)
    - One to one (1:1)
  4. Constraint: A restriction placed on the data
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4
Q

What are Business Rules?

A

Description of policies, procedures or principles within a specific organization.

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5
Q

Translating business rules into data model components

A
  1. Generally, nouns translate into entities.
  2. Verbs translate into relationships among entities.
  3. Relationships are bidirectional.
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6
Q

Two questions to identify the relationship type

A
  1. How many instances of B are related to one instance of A?

2. How many instances of A are related to one instance of B?

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7
Q

What is the Entity Relationship Model?

A

It is the widely accepted standard for data modeling.

It is a graphical representation of entities and their relationships in a database structure.

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8
Q

Entity set

A

Collection of like entities that are usually mapped to a relational table.

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9
Q

Entity instance

A

A row in a table

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10
Q

Entity attribute

A

A column in a table

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11
Q

What is connectivity?

A

It describes the relationship classification/type

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12
Q

What is cardinality?

A

Expresses minimum and maximum number of entity occurrences associated with one occurrence of related entity.

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