SAD 5

• Systems Analysis and Design

  • Introduction
  • Project Initiation
  • Requirements Gathering
  • Process Modeling
  • Data Modeling
  • System Design
  • System Implementation
  • Project Management in Systems Development
  • Agile and Iterative Development
  • Emerging Trends in SAD
• Model


  • An abstraction (simplified representation) of a real-world object or event
  • Useful in understanding complexities of the real-world environment
• Data model


  A diagram that displays a set of tables and the relationships between them

  
• Data Modelling


  1. Conceptual Data Model

  2. Logical Data Model

  3. Physical Data Model

  
• Conceptual Data Model


  • Provides a high-level, abstract view of the entire data environment
  • Focuses on entities, attributes, and relationships between them
  • Independent of specific database management systems (DBMS)
  • Used to capture business requirements and concepts

  
• Logical Data Model


  • Translates the conceptual data model into a more detailed representation
  • Aligned with underlying database technology
  • Defines the structure of data using tables, columns, keys, and relationships
  • Typically represented using entity-relationship diagrams or relational data models

  
• Physical Data Model


  • Refines the logical data model by specifying physical implementation details
  • Defines storage structures, indexing mechanisms, and optimization techniques
  • Represents how data will be stored and accessed in the actual database system
  • Considers performance, scalability, and security aspects

  
• Data modeling


  • A process of creating a visual representation of data structures required for a database
  • Helps to articulate the characteristics of data, business rules, and how information is organized within the database
  • Includes defining data, relationships between data, meanings, and limitations

  
• Approaches to data modeling

  • Entity-relationship modeling
  • Relational modeling
  • Dimensional modeling
  • Object-oriented modeling
  • Graph modeling

  
• Entity


  A table
• Attribute


  A column
• Relationship


  A line
• Entity-Relationship Diagrams (ERDs) are graphical representations used to model the data schema of a system

  
• Entity


  Anything (people, places, objects, events, etc.) about which we store information
• Attribute


  Data objects that either identify or describe entities (properties of an entity)
• Relationship


  • Associations between entities
  • Typically indicated by a verb connecting two or more entities
• Cardinality


  • The number of occurrences in one entity which are associated to the number of occurrences in another
  • One-to-one (1:1), one-to-many (1:M), and many-to-many (M:N)
• One-to-one (1-to-1)


  • Each entity in E1 is associated with 0 or one entity in E2, and vice versa
• One-to-many (1-to-m)

  • Each entity in E1 is associated with zero or more entities in E2, and each entity in E2 is associated with at most one entity in E1
• Many-to-many (m-to-n)

  • Each entity in E1 is associated with 0 or more entities in E2, and vice versa
• Designing ERDs

  1. Gather requirements

  2. Identify entities and attributes

  3. Define relationships

  4. Draw the ERD

  5. Validate and refine
• A preliminary or initial stage of using the Unified Modeling Language (UML) in software development or system design is called UML First Pass
• Activities in UML First Pass

  • Requirement Analysis
  • Conceptual Modeling
  • Use Case Diagrams
  • Class Diagrams
  • Sequence Diagrams
  • Activity Diagrams
  • State Machine Diagrams
• Use case diagrams


  Represent the functionality of the system from user's point of view
• Components of the Use Case Diagrams

  • Actors
  • Use Cases
  • Relationships (Associations, Inclusions, Generalizations)
  • System Boundary
• Class diagrams


  Represent the structure of the system
• Sequence diagram

  Represent the behavior of a system as messages ("interactions") between different objects
• Statechart diagrams

  Represent behavior of a single object with interesting dynamic behavior
• Activity diagrams


  Represent sequence in which activities are performed and the conditions or triggers that initiate each activity