Relational Database Design and Modeling for Software Engineers
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Introduction
Course Overview
Before the Advent of Database
What is a Database?
Database management systems (DBMS)
Overview of Relational Databases
Relational Vs. Non-Relational Databases
Introduction to Data Modeling
Levels of Data Modeling
Data Modeling Process
Best Practices in Data Modeling
Quiz
Introduction to ER Models
Entities, Attributes, and Relationships
Cardinality and Participation
Attributes of Relationship Types
Weak Entity Types
Creating an ER Diagram for Employee Management System
Quiz
Introduction to the Relational Model
Relations, Tuples, and Attributes
Keys in Relational Databases
Relational Integrity Constraints
Converting ER Diagrams to Relational Model
Best Practices for ER Diagrams to Relational Models
Quiz
Introduction to Functional Dependency
Types of Functional Dependencies
Inference Rules for Functional Dependencies
Closure of Attribute Sets
Quiz
Introduction to Normalization
First Normal Form (1NF)
Second Normal Form (2NF)
Third Normal Form (3NF)
Boyce-Codd Normal Form (BCNF)
Higher Normal Forms (4NF, 5NF)
Exercise 1
Solution to Exercise 1
Exercise 2
Solution to Exercise 2
Designing a Hospital Management System
Designing a Hotel Management System
Designing a Bank Management System
Designing an Instagram
Designing an E-commerce Platform
Designing an Online Food Delivery System
Before the Advent of Database

Traditional File System

Before databases became the backbone of data storage and retrieval, the traditional file system was the primary way organizations stored data. This system involved storing data in files and directories on physical media such as hard drives. Each application had its own set of files, often organized in a hierarchical or sequential manner. Data was managed through a combination of file formats and custom software programs to read and write information.

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  • Structure: Files were structured in formats like text files, CSVs, and binary files.
  • Access: Data access was typically sequential or indexed for improved retrieval in some systems.
  • Management: Each department or application maintained its own files independently.

Disadvantages of the File System

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While the traditional file system worked for basic data storage needs, it presented significant limitations as data complexity and usage increased:

  1. Data Redundancy and Inconsistency:

    • Redundant Storage: Multiple copies of the same data could be stored in different files, leading to unnecessary storage consumption.
    • Inconsistency: Updates to data in one file were not automatically reflected in other files, causing discrepancies.
  2. Data Isolation:

    • Lack of Integration: Data scattered across various files and formats made it difficult to integrate and retrieve related information.
    • Complex Access: Retrieving related data often required complex and manual programming.
  3. Difficulty in Data Access:

    • Programming Dependency: Accessing data required significant programming effort, limiting quick data retrieval.
    • Sequential Access Limitations: Searching large files was slow and inefficient, especially when data was stored sequentially.
  4. Lack of Security:

    • No Centralized Control: File systems did not have a unified way to enforce security or control data access.
    • Vulnerability: Data was often exposed to unauthorized access without proper access control mechanisms.
  5. Limited Data Integrity and Reliability:

    • Error-Prone: Maintaining data integrity required manual programming, which was error-prone and unreliable.
    • Data Corruption: Files were more susceptible to corruption, especially if data was accessed concurrently by multiple programs.
  6. Challenges with Data Scalability:

    • Hard to Scale: The file system was not designed to handle large-scale data effectively.
    • Manual Management: Growth in data volume made file management cumbersome and complex.

Why the Database Was Invented

The limitations of traditional file systems paved the way for the invention of database systems. As data grew in volume, complexity, and importance, a more organized, reliable, and efficient system was required.

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Databases were developed to:

  • Reduce Data Redundancy: Centralize data storage to ensure that the same piece of data is not duplicated across multiple locations.
  • Improve Data Consistency: Establish a single source of truth so that data changes are reflected across all systems using it.
  • Enhance Data Access: Provide more flexible, faster, and structured query methods through languages like SQL.
  • Support Concurrent Access: Allow multiple users and applications to access and modify data simultaneously without data integrity issues.
  • Strengthen Security and Authorization: Offer robust mechanisms for securing data and controlling access based on user roles.
  • Ensure Data Integrity and Reliability: Maintain data accuracy through constraints, relationships, and checks automatically enforced by the database system.
Course Overview
What is a Database?
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On this page

Traditional File System

Disadvantages of the File System

Why the Database Was Invented