Systems analysis and development CIS210 ch 09

CIS 210 Systems Analysis and Development Week 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 – – – – – – • Types of operations – – – – • Object State Behavior Object class Class diagram Operation 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 ... 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... 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... Naming and defining types Attributes • Naming and defining attributes • Multi-valued attributes – Candidate keys and identifiers • Relationships – Associations Conceptual Data Modeling and the