Learn how data is stored, queried, and protected — from the relational model and SQL to ACID transactions, normalisation, and query optimisation.
The relational model, tables, keys, and writing your first SQL queries.
Databases & DBMS — SQL, ACID & Indexing
Learn the relational model, write real SQL queries, understand ACID transactions, normalization, and how indexes make queries fast.
SQL Basics — CREATE, SELECT, UPDATE & DELETE
Your first complete SQL guide. Learn to define tables, insert data, filter with WHERE, sort, paginate, and aggregate — with real examples.
Joins, aggregates, subqueries — the tools for real-world queries.
Schema design, normalisation, and making data changes safe.
Database Design — ER Diagrams & Normalisation
Model your domain before writing SQL. Learn ER diagrams, 1NF through BCNF, and when (and how) to denormalise for performance.
Transactions, ACID & Concurrency Control
Deep dive into ACID guarantees, isolation levels, MVCC, and deadlocks. Know exactly what your database does when things go wrong.
How indexes work internally, query planning, and making queries fast.
Database Indexes & Query Optimisation
How B-Tree indexes work internally, composite vs covering indexes, EXPLAIN output, and the rules for knowing when to add — or remove — an index.
Query Processing & Optimisation — Parse, Plan & Execute
Follow a SQL query from text to result: parsing, logical/physical planning, cost estimation, join algorithms, and reading EXPLAIN output.
Beyond SQL: NoSQL stores, stored procedures, triggers, and replication.
NoSQL Databases — Document, Key-Value, Column & Graph Stores
Understand when to choose NoSQL over relational. Covers MongoDB, Redis, Cassandra, and Neo4j with CAP theorem and consistency trade-offs.
Stored Procedures, Triggers & Views
Move logic into the database with stored procedures and triggers. Learn when they help, when they hurt, and how views simplify complex queries.
Database Replication — Leader-Follower, Multi-Leader & Consensus
How databases stay available and consistent across multiple nodes. Covers replication lag, failover, read replicas, and Raft consensus.