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

Overview 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

Summary Conceptual Data Modeling Gathering Information E-R Modeling Supertypes and Subtypes Business Rules The Role of Packaged Conceptual Data Models Object Modeling