Chapter 4: Design – Exam Revision Notes

1. Introduction to System Design

• Objective: Transform analysis models into blueprints for building the system.
  
• Focus Areas:
  
  • Database design
    
  • Forms and reports design
    
  • Interface and dialogue design
    
• Goal: Ensure the system is efficient, usable, and meets requirements.
  

2. Designing Databases

• Relational Database Model: Data stored in tables (relations); each table has rows (tuples) and columns (attributes).
  
• Normalization: Process to eliminate redundancy and improve data integrity.
  
  • 1NF – Remove repeating groups
    
  • 2NF – Remove partial dependency
    
  • 3NF – Remove transitive dependency
    
• Transforming E-R Diagrams into Relations:
  
  • Each entity → Table
    
  • Attributes → Columns
    
  • Relationships → Foreign keys or separate tables for many-to-many relationships
    
• Merging Relations: Combine related tables where appropriate to optimize queries.
  
• Physical Database Design:
  
  • Design physical tables and fields
    
  • Define data types, sizes, indexes
    
  • Consider performance, storage, and access methods
    

3. Designing Forms and Reports

• Forms: User interface for data entry and retrieval.
  
• Reports: Structured presentation of processed information.
  
• Design Guidelines:
  
  • Logical layout of fields
    
  • Consistency in formatting
    
  • Minimize user errors
    
  • Use visual aids (colors, fonts) for readability
    
• Usability Assessment: Ensure forms and reports are intuitive and easy to use.
  

4. Designing Interfaces and Dialogues

• Interface Design: Focus on interaction between user and system.
  
• Dialogue Design: How inputs and outputs are structured for tasks.
  
• Interaction Methods and Devices:
  
  • Keyboard, mouse, touchscreens
    
  • Menus, buttons, checkboxes, radio buttons
    
• Graphical Environment Design:
  
  • Use GUI components (forms, windows, menus)
    
  • Consistency in navigation and feedback
    
  • Minimize cognitive load on users
    
• Design Principles:
  
  • Clarity – Users must understand easily
    
  • Feedback – System responds to user actions
    
  • Flexibility – Support different user preferences
    
  • Error Handling – Provide helpful messages
    

5. Key Points

• Design bridges analysis models and actual implementation.
  
• Database design ensures data integrity and efficiency.
  
• Forms and reports design enhance usability and productivity.
  
• Interface and dialogue design improves user satisfaction and reduces errors.
  
• Effective design reduces development cost, maintenance effort, and rework.