Master SQL & NoSQL, then nail the interview
Transactions, ACID, isolation levels, locking & MVCC, distributed transactions, SQL and NoSQL — full story-driven chapters to learn it from scratch, plus a real interview question bank to prove you know it.
What's inside
Learn From Scratch
Story-driven chapters that build every concept from first principles — the bank-counter story, isolation levels, locking, MVCC, distributed transactions — with code examples throughout.
Real Interview Questions
A curated question bank drawn straight from the material, with an AI tutor that builds a complete zero-to-expert answer for every question, on demand.
Diagrams, Chat & Flashcards
Generate a visual diagram for any topic or question, ask the AI tutor a follow-up, and review with spaced-repetition flashcards that bring weak spots back sooner.
Categories
Transaction Mastery
ACID, isolation levels, locking & MVCC, Spring @Transactional internals, distributed transactions (2PC, Saga, Outbox/CDC), and Kafka transactions — from the bank-counter story to production incident response.
SQL
DDL/DML, JOINs, subqueries, indexes, transactions, isolation levels, locking, window functions, CTEs, query performance, and database design — PostgreSQL, MySQL, SQL Server & Oracle.
NoSQL
MongoDB, Redis, Cassandra, Neo4j, CAP theorem, BASE, distributed systems, caching patterns & CQRS.
MongoDB
Document model, CRUD & aggregation, indexing, replica sets & sharding, multi-document transactions, schema design, performance, and Spring Data MongoDB.
Redis
Core data structures, persistence (RDB/AOF), replication & clustering, caching patterns & eviction, Pub/Sub & Streams, transactions & Lua scripting, and Spring Data Redis.
Cassandra
Query-first data modeling, partition & clustering keys, replication factor & tunable consistency levels, the write path & compaction, CQL, and Spring Data Cassandra.
Neo4j
The graph data model & Cypher basics, traversals & common query patterns, indexes & query performance, and Spring Data Neo4j.
SQL Practice Problems
150 solved SQL problems across Beginner, Intermediate, Advanced, and Expert & Real-World tiers — every solution executed against a real dataset, with the actual output and a full explanation for each.
Frequently Asked Questions
What are the most commonly asked database interview questions?
Interviewers most often ask about ACID properties, transaction isolation levels (dirty reads, phantom reads), the difference between SQL and NoSQL, indexing strategies, normalization vs denormalization, and how distributed transactions work across microservices — all covered here with full learning chapters and a dedicated interview question bank.
Is SQL or NoSQL more important for interviews?
Both — most product companies expect you to know relational fundamentals (SQL, joins, transactions, ACID) AND when a NoSQL model (MongoDB, key-value, wide-column) actually fits better. This course covers both tracks with story-driven chapters and a combined interview question bank.
What is the best way to learn database transactions for interviews?
Start from a concrete story (like a bank transferring money between two accounts) before the formal definitions of ACID and isolation levels — that's exactly how the Transactions chapters here are structured, building from real-world intuition to the technical and interview-ready definitions.