Unit 3: System Design and Data Management

System Design and Data Management

System design is a critical phase in system development that focuses on defining the architecture, components, interfaces, and data flows of the information system. Good system design ensures efficiency, usability, and scalability.

Principles of System Design

Effective system design should follow these core principles:

Principle	Description
Modularity	Break the system into smaller, manageable modules for easier maintenance.
Simplicity	Keep design straightforward to minimize errors and improve usability.
Flexibility	Allow easy modifications as business needs change.
Consistency	Maintain uniform design standards for interfaces, data structures, and processes.
Efficiency	Optimize resource use (memory, processing time, network bandwidth).
Security & Integrity	Ensure data confidentiality, integrity, and protection against unauthorized access.
User-Centric Design	Focus on ease of use and clear interfaces for end-users.

Tip: Relate principles to real-world systems like ERP or e-commerce platforms.

Input-Output Design for Business Applications

Input-Output (I/O) design ensures that data enters the system correctly and output is meaningful and actionable.

Input Design

• Purpose: Capture accurate and relevant data for processing.

Techniques:

• Validation checks (range, type, format)
• Input forms (online forms, paper-based forms, mobile apps)
• Barcode/RFID scanning for automated data capture

Key Consideration: Minimize errors and improve efficiency.

Output Design

• Purpose: Present processed information clearly for decision-making

Types of Output

• Reports (daily sales report, inventory summary)
• Screens (online dashboards, alerts)
• Printed outputs (invoices, order slips)

Design Guidelines

• Clarity and readability
• Proper formatting and layout
• Timeliness (real-time vs. periodic outputs)

Example: An e-commerce system takes user orders (input), processes payment, and generates invoices & shipping labels (output).

Design of Online Catalogues

Online catalogues are digital representations of products or services for customer access. Proper design ensures usability and increases sales.

Key Elements

1. User Interface (UI): Intuitive navigation, search filters, categories.
2. Product Information: Clear descriptions, specifications, pricing, images.
3. Data Management: Maintain accurate inventory information., Use relational databases for product, category, and supplier details.
4. Accessibility & Performance: Fast loading pages, mobile-friendly design, Support multiple platforms (web, mobile apps).
5. Integration: Connect with inventory, billing, and logistics systems for real-time updates.

Example: Amazon, Flipkart, or any B2B catalogue uses structured design with categories, search, filters, and real-time stock updates.

Summary Table

Aspect	Key Points	Example / Tools
System Design Principles	Modularity, simplicity, flexibility, security, user-centric	ERP, CRM systems
Input Design	Accurate data capture, validation, forms, automation	Online forms, RFID, barcodes
Output Design	Clear, timely information for decision-making	Dashboards, reports, invoices
Online Catalogue Design	UI/UX, product info, database integration, performance	Amazon, Flipkart, Magento, Shopify

File Organization

File organization defines how data is stored and accessed in files on storage devices. Choosing the right method affects retrieval speed, storage efficiency, and system performance.

Types of File Organization

Type	Description	Advantages	Example
Sequential File Organization	Records stored one after another	Simple, easy to maintain	Payroll processing, billing reports
Indexed File Organization	Uses an index to quickly locate records	Faster search than sequential	Student database with roll number index
Direct / Random File Organization	Records stored with a key-based address	Immediate access to data	ATM account details, bank databases
Hashed File Organization	Uses a hash function to compute record location	Efficient for large datasets	Employee databases, large inventory systems

Tip: Relate file organization to business application needs (e.g., sequential for reporting, random for banking).

File Design Techniques

File design involves structuring data files to support system requirements efficiently.

Key Techniques

1. Normalization: Organizes data to reduce redundancy and improve integrity Example: Separate employee details, department details, and salary tables.
2. Data Structuring: Use records, fields, and keys to organize data., Primary keys uniquely identify records; foreign keys link related tables.
3. Access Methods Design: Define how users and programs retrieve data , Methods: sequential access, indexed access, random access.
4. Backup and Recovery Planning: Ensure data safety in case of system failure. Example: Regular database backups, RAID storage, cloud replication.

Database Concepts

Databases are centralized repositories of data, supporting efficient storage, retrieval, and management.

Key Concepts

• Database: Collection of related data stored systematically.
• DBMS (Database Management System): Software that manages databases (e.g., Oracle, MySQL, SQL Server).

Data Models: Define how data is structured and related.

• Hierarchical Model
• Network Model
• Relational Model (most popular in business applications)
• Object-Oriented Model

Benefits of Databases

• Minimize redundancy and data inconsistency.
• Improve data integrity and security.
• Support complex queries and reporting.
• Facilitate multi-user access and concurrency control.

Database Design

Database design is the process of creating an efficient database structure to meet business needs.

Steps in Database Design

1. Requirement Analysis: Gather data needs from stakeholders.
2. Conceptual Design: Create ER (Entity-Relationship) diagrams showing entities, attributes, and relationships.
3. Logical Design: Convert ER diagrams into tables, primary keys, and foreign keys.
4. Normalization: Remove redundancy and ensure data integrity.
5. Physical Design: Determine storage structures, indexes, and access methods.
6. Implementation & Testing: Build database in DBMS and validate functionality.

Example: A retail store database with tables for Customers, Products, Orders, and Payments linked via primary and foreign keys.

Summary Table

Topic	Key Points	Example / Tools
File Organization	Sequential, Indexed, Direct, Hashed	Payroll system, Banking accounts
File Design Techniques	Normalization, Data Structuring, Access Methods, Backup	Employee, Inventory files
Database Concepts	DB, DBMS, Data Models	Oracle, MySQL, SQL Server
Database Design	ER Diagrams, Logical & Physical Design, Normalization	Retail store DB, Hospital DB

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Exam Tips

1. Always relate file/database concepts to real business applications.
2. Draw ER diagrams and table structures for clarity.
3. Explain advantages of DBMS over flat file systems.
4. Highlight file organization choice based on application type (transactional vs reporting).