Database Systems SQL

Overview

This repository is a student learning portfolio for database systems and SQL. It contains clean examples of schema design, relationships, constraints, joins, aggregation, and basic normalization ideas.

I am building this as part of my GitHub student portfolio for bursaries, internships, graduate programmes, and future Honours opportunities.

Why I Created This Repository

Database systems are important in software engineering, full-stack development, data-driven applications, and academic computer science. I created this repository to practise designing relational databases and writing SQL queries in a clear, explainable way.

Current Scope

This foundation repo uses a Student Course Registration System as the main mini-project.

It demonstrates:

• Tables and columns
• Primary keys
• Foreign keys
• NOT NULL constraints
• UNIQUE constraints
• One-to-many relationships
• Many-to-many relationships
• Joins
• Filtering
• Sorting
• Aggregation with COUNT and AVG
• Introductory normalization thinking

Repository Structure

database-systems-sql/
|-- README.md
|-- notes/
|   |-- database-fundamentals.md
|   |-- normalization.md
|   `-- sql-query-notes.md
`-- student-course-registration/
    |-- README.md
    |-- schema.sql
    |-- seed.sql
    `-- queries.sql

How To Run The SQL Scripts

Use a SQL database tool such as MySQL Workbench, DBeaver, pgAdmin, SQLite tools, or another database environment that supports standard SQL-style scripts.

Run the scripts in this order:

1. student-course-registration/schema.sql
2. student-course-registration/seed.sql
3. student-course-registration/queries.sql

The SQL is written to stay close to standard SQL concepts, but small syntax adjustments may be needed depending on the database system you use.

What I Learned

• How to plan tables around real relationships.
• How primary keys uniquely identify rows.
• How foreign keys connect related tables.
• How a junction table models a many-to-many relationship.
• How joins combine data from multiple tables.
• How grouping and aggregation can answer useful questions.
• Why normalization helps reduce duplicated and inconsistent data.

Planned Extensions

This repository currently focuses on database foundations. Future improvements may include:

• Cinema booking database mini-project
• Clinic appointment database mini-project
• More advanced joins
• Views
• Transactions
• Stored procedures
• Indexing basics
• Database design case studies from CineBook and CASS