Database Systems

Almost every application in existence stores data. This course teaches you to design, query, and understand the systems that do it well.

You'll begin by understanding why databases exist at all what problems they solve that plain files can't then move into SQL, the universal language of relational databases. From there, you'll learn how to design a proper schema from scratch, write queries that span multiple tables, and understand the internals that determine why some databases fly and others crawl.

This course is practical from the first lesson. You'll be writing real SQL by the end of Unit 1.

What you'll cover:

• Why databases exist and how they differ from file storage
• The relational model: tables, rows, columns, and data types
• SQL fundamentals: SELECT, WHERE, INSERT, UPDATE, DELETE, ORDER BY, NULL
• Database design: entities, relationships, cardinality, ER diagrams
• Normalisation from 1NF to 3NF and why it matters
• Joins: INNER, LEFT, RIGHT, FULL
• Aggregate functions, HAVING, and subqueries
• Transactions, ACID properties, indexes, views, and constraints

Who this is for: Developers building applications that store data, students studying CS or data-related fields, and anyone who wants to go from "I can write a SELECT statement" to genuinely understanding relational databases.

Prerequisites: No prior database experience needed. Basic programming literacy is helpful for the SQL sections.