Systems analysis and development CIS210 ch 09

CIS 210Systems Analysis and Development Week 6 Part I Structuring Systems Data Requirements... Objectives • Upon completion of part I you will be able to: – Understand and be able to exp

CIS 210

Systems Analysis and Development

Week 6 Part I

Structuring Systems Data Requirements

Objectives

• Upon completion of part I you will be able to:

– Understand and be able to explain the concepts related to data modeling terms

– Understand and be able to draw entity relationship diagrams – Understand and be able to explain the concepts related to

conceptual data modeling

– Understand and be able to explain the concepts related to

distinguish between unary, binary, and ternary relationships – Understand and be able to explain the concepts related to

defining rules for business use in E-R diagrams

• Data Modeling: Why is it Important?

– Characteristics of data are crucial

– Data are most complex aspects of information systems

– Data characteristics reasonably permanent

• E-R Diagramming / Class Diagramming

– Explain structure of data

– Mastery is crucial to success

Conceptual Data

Modeling

• What is a Conceptual Data Model

– Representation of organizational data – Rules and meaning of data

• Conceptual Data Modeling Process

– Develop model for existing system – Develop model for new system

– Encapsulates all SDLC phases

• Deliverables

– E-R diagram

– Entries in data dictionary

Gathering Information

• Top-Down Approach

– Understanding of the nature of the business – No specific information requirements

• Bottom-Up Approach

– Specific business documents

• Computer displays

• Reports

• Business forms

Introduction to E-R Modeling

• Overview

– E-R model

– E-R Diagram

• Entities

– Entity type

– Entity instance

– Naming and defining types

– Attributes

• Naming and defining attributes

• Multi-valued attributes

– Candidate keys and identifiers

• Relationships

– Associations

Conceptual Data Modeling and the ER Model

• Degree of Relationship

– Unary

– Binary

– Ternary

• Cardinalities in Relationships

– Minimum

– Maximum

• Naming and Defining Relationships

– Naming guidelines

– Guidelines for defining

• Associative Entities

Representing Supertypes & Subtypes

• Subtype

– Sub grouping of entities

• Supertype

– Generic entity type

• Relationship Rules

– Total specialization

– Partial specialization

– Disjoint rule

– Overlap rule

Business Rules

• Types of Business Rules

– Entity integrity

– Referential integrity constraints

– Domains

• Domain definitions

– Triggering operations

• Components

– User rule – Event – Entity name – Condition – Action

Packaged Conceptual

Data Models

• Overview

– Comparatively low cost

– Generic data models

– Developed by specialists

• Types of Packaged Data Models

– Universal

– Industry specific

• Benefits

– Time

– Cost

– Quality

Object Modeling

• Representing Objects and Classes

– Object

– State

– Behavior

– Object class

– Class diagram

– Operation

• Types of operations

– Constructor

– Query

– Update

– Scope

• Representing

– Associations

– Association Classes

– Derived Attributes, Associations, and Roles

– Generalization

• Conceptual Data Modeling

• Gathering Information

• E-R Modeling

• Supertypes and Subtypes

• Business Rules

• The Role of Packaged Conceptual Data Models

• Object Modeling