Lesson 3 | Data Modeling Concept

Question 1

Types of Data Models

Answer 1

Entity-Relationship (ER) Model
UML (Unified Modeling Language

Question 2

• Only addresses data and relationships
• Classic, simplest
• Best for deriving a sound table design
• Many extensions/variation exist
• Basis for most other modeling approaches

Answer 2

Entity-Relationship (ER) Model

Question 3

• Class Models
• Goes beyong data, also models behaviors

Answer 3

UML (Unified Modeling Language)

Question 4

• Technology Independent
• Contains more detail than the Conceptual Data Model
• Considered by many to be just an expanded conceptual data model
• Defines Entities and their attributes
• Defines Relationsips and Cardinality
• Defines Contraints
• Generally completed as a document Entity Relationship Model or Diagram

Answer 4

Logical Data Model

Question 5

• Documentation of the structure of the data
• Used to communicate the design
• Serve as the basis for data model implementation

Answer 5

Entity Relationship Model

Question 6

• Entities effectively become tables
• Attributes describe entities and become fields (columns) in table
• Relationhips link tables on a common attribute or “key” and become formal constraints (part of the business rules)

Answer 6

Entity Relationship Diagram (Relation Database Context)

Question 7

What is the Data type for:
Site Name: Little Bear River near Wellsville

Answer 7

Char()

Question 8

What is the Data type for:
Site Code: USU-LBR-Wellsville

Answer 8

varchar()

Question 9

What is the Data type for:
Lattitude: 41.643457

Answer 9

Decimal() | Float

Question 10

What is the Data type for:
Longitude: -111.917649

Answer 10

Float() | Decimal()

Question 11

What is the Data type for:
Elevation: 1365 m

Answer 11

int(), since if we use “varchar” it becomes complex, as the user needs to know what unit they should use.

Question 12

What is the Data type for:
State: UTAH

Answer 12

char()

Question 13

What is the Data type for:
County: Cache

Answer 13

char()

Question 14

What is the Data type for:
Description:: Attached to SR101 bridge

Answer 14

varchar()

Question 15

What is the Data type for:
Site type: Stream

Answer 15

char()

Question 16

What is the symbol for Zero to Many Crows foot

Answer 16

—–o-<– |

Question 17

What is the symbol for the One to Many Crows Foot

Answer 17

——|–<–

Question 18

What is the symbol for one to one crows foot

Answer 18

——|-|–

Question 19

What is the symbol for Zero to One Crows Foot

Answer 19

—–o–|–

Question 20

• Multiple notation systems are used
• Each software program is a little different
• Most common is “Crows Foot”

Answer 20

ER Diagram Relationship Notation

Question 21

Maximum number of times an instance in one entity can be associated with instance in the related entitiy

Answer 21

Cardinality

Question 22

Minimum number of times an instance in one entity can be associated with instance in the related entity

Answer 22

Participation

Question 23

• Can ONLY have values of 1 or many
• Located closest to the entity in Crows Foot notation

Answer 23

Cardinality

Question 24

• Indicates whether an instance of an entity MUST participate in the relationship
• Can ONLY have the values of 0 or 1

Answer 24

Participation

Question 25

- Each row in a table should have an attribute that is a persistent, unique identifier - the ____

Answer 25

Primary Key

Question 26

Primary Key is in the ____ Table

Answer 26

Parent

Question 27

Foreign key is in the _____ Table

Answer 27

Child

Question 28

Primary key usually consist of what data type

Answer 28

Int() | Integer Values

Question 29

What are the categories of data model

Answer 29

- Relational Model - ER Model - Object Based Model - Semi Structured Model

Question 30

- Collection of Tables - Tables represent both data and relationships - Multiple columns with unique names - Tables = Relations - Record-Based model - fixed format records of several types - Each record type defines a fixed number of fields, or attributes - Most widely used

Answer 30

Relational MOdel

Question 31

- Collection of basic objects called entities and its relationships - An entity is a real world thing or object - Distinguishable from the other objects - Widely used in database design

Answer 31

Entity-Relationship Model

Question 32

- OOP Languages - C++, Java, C#, etc - Need for Object Oriented Data model - Object Based model = ER model and Object Oriented Features - Object Relational Data Model = Object Based Model + Relational MOdel

Answer 32

Object-Based Model

Question 33

- Specification of data - Individual data items of the same type may have different sets of attributes - Usign of 2 different languages - Contrast to ER Model, Relational MOdel and Object Orirented Model - XML

Answer 33

Semistructure Data Model

Question 34

Steps in Data Model Design

Answer 34

1. Identify entities 2. Identify relationships among entities 3. Determine the cardinality and participation of relationships 4. Designate keys / identifiers for entities 5. List attributes of entities 6. Identify constraints and business rules