Overview of database development
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Overview of Database Development. Data Modeling and Relational Database Design. Objectives. Describe the phases of the database development process Describe the phases of the application development process Explain conceptual data modeling and database design. Strategy and Analysis.

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Overview of database development

Overview of Database Development

Data Modeling and Relational Database Design


Objectives

Objectives

  • Describe the phases of the database development process

  • Describe the phases of the application development process

  • Explain conceptual data modeling and database design


System development life cycle

Strategy

and

Analysis

Design

Build

and

Document

Transition

Production

SYSTEM DEVELOPMENT LIFE CYCLE


Database development process

Conceptual

Data Modeling

Function Modeling

Database Design

Application Design

Database Build

Application Build

Database Development Process

Business Requirements

Information

Process

Cross-checking

ER model,

entity definition

Function hierarchy,

function definition

Module (screen, report, menu, program design)

Table, index,

view

Cross-checking

Database

Application

Operational System


Database development process1

Conceptual Data Modeling

Database Development Process

Business Information Requirements

Business view

Systems view

Logical Database Design

Physical Database Build

Operational Database


Terminology

Terminology

CONCEPTUAL

LOGICAL

(Business view)

(Systems view)

ANALYSIS

DESIGN

ENTITY

TABLE

RELATIONSHIP

FOREIGN KEY

ATTRIBUTE

COLUMN

PRIMARY KEY

UNIQUE

IDENTIFIER

UNIQUE KEY


Information models

Information Models

  • Organize thought processes

  • Accurately model business data

  • Communicate with stakeholders

  • Analyze the scope

  • Provide sound basis for system design


Goals of conceptual data modeling

Goals of Conceptual Data Modeling

  • Robust syntax

  • User communication

  • Ease of development

  • Definition of scope

  • Integration of multiple applications


Modeling basic entities and attributes

Modeling Basic Entities and Attributes


Overview

Overview

  • Why conceptual modeling?

  • Introduction of the Key role players:

    • Entities

    • Attributes

    • Relationships


Why create a conceptual model

Why Create a Conceptual Model?

  • It describes exactly the information needs of the business

  • It facilitates discussion

  • It helps to prevent mistakes, misunderstanding

  • It forms important “ideal system” documentation

  • It forms a sound basis for physical database design

  • It is a very good practice with many practitioners


Conceptual model between dream and reality

Conceptual Model Between Dream and Reality...


Entity relationship modeling

Entity Relationship Modeling

  • Models business,not implementation

  • Is a well-established technique

  • Has a robust syntax

  • Results in easy-to-read diagrams…

  • ...although they maylook rather complex at first sight


Goals of entity relationship modeling

Goals of Entity Relationship Modeling

  • Capture all required information

  • Information appears only once

  • Model no information that is derivable from other information already modeled

  • Information is in a predictable, logical place


Conceptual data models

Server

CONCEPTUAL DATA MODELS

Model of systemin client’s mind

Entity model ofclient’s model

Table modelof entity model

Tables on disk


Database types

Database Types

ER Model

Network

Hierarchical

Relational


Entity relationship model

ENTITY RELATIONSHIP MODEL

  • Create an entity relationship diagram from business specifications or narratives

DEPARTMENT

#* number

*name

olocation

EMPLOYEE

#* number

*name

ojob title

assigned to

composed of

  • Scenario

    • “. . . Assign one or more employees to a department . . .”

    • “. . . Some departments do not yet have assigned employees . . .”


Entity

Entity

  • An Entity is:

    • “Something” of significance to the business about which data must be known.

    • A name for the things that you can list.

    • Usually a noun.

  • Examples: objects, events

  • Entities have instances.


Identify and model entities

Identify and Model Entities

  • Identify a noun

    • Is it significant?

    • Is there information about it that the business needs to keep?

    • Is it a group or an instance?

  • Name the entity

  • Write a description of it

  • Identify a few attributes

  • Draw a soft box for it


Overview of database development

Entity Instances

Head office

Finance

Personnel

Sales

EMPLOYEE

DEPARTMENT


Identifying a unique instance

EMPLOYEE

badge number

name

date of birth

salary

Identifying a Unique Instance


Entities and instances

Entities and Instances

PERSON

PRODUCT

PRODUCT TYPE

EMPLOYMENT CONTRACT

JOB

SKILL LEVEL

TICKET RESERVATION

PURCHASE

ELECTION

PRINTER PREFERENCE

DOCUMENT VERSION

Mahatma Gandhi

2.5 x 3.5 mm copper nail

Nail

My previous contract

Violinist

Fluent

Tonight: Hamlet in the Royal

The CD I bought yesterday

For parliament next fall


Entities and sets

Entities and Sets

  • An entity represents a set of instances that are of interest to a particular business.

JOB

manager

cook

waitress

dish washer

financial controller

porter

waiter

piano player


Attribute

Attribute

  • Also represents something of significance to the business

  • Is a single valued property detail of an entity

  • Is a specific piece of information that:

    • Describes

    • Quantifies

    • Qualifies

    • Classifies

    • Specifies

      an entity.


Attribute examples

Attribute Examples

Entity

EMPLOYEE

CAR

ORDER

JOB

TRANSACTION

EMPLOYMENT CONTRACT

Attribute

Family Name, Age, Shoe Size, City, Email, …

Model, Weight, Catalog Price, …

Order Date, Ship Date, …

Title, Description, ...

Amount, Transaction Date, …

Start Date, Salary, ...


Entity representation in diagram

EMPLOYEE

JOB

ELECTION

TICKET

RESERVATION

ORDER

JOB ASSIGNMENT

Entity Representation in Diagram

  • Drawn as a “softbox”

  • Name singular

  • Name inside

  • Neither size, nor position has a special meaning

During design, entities usually lead to tables.


Attributes in diagrams

Attributes in Diagrams

EMPLOYEE*family Name address birth Dateoshoe Sizeo email

JOBtitleo description

*

o

*

*

Mandatory attribute, that is, known and available for every instance

Optional attribute, that is, unknown or unimportant to know for some instances

o

During design, attributes lead to columns.


Entity relationship modeling conventions

ENTITY RELATIONSHIP MODELING CONVENTIONS

Entity

Soft box

Singular, unique name

Uppercase

Synonym in parentheses

Attribute

Singular name

Lowercase

Mandatory marked with “*”

Optional marked with “o”

DEPARTMENT

#* number

*name

olocation

EMPLOYEE

#* number

*name

ojob title

assigned to

composed of

Unique Identifier (UID)

Primary marked with “#”

Secondary marked with “(#)”


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