Databases Decoded: Prepare for database interviews on one running e-commerce database, CampusCart

Database interviews do not reward memorized definitions. They test whether you can write SQL, explain what the database engine actually does, and design systems that survive real-world scale.Databases Decoded: DBMS, SQL and System Design for the Technical Interview bridges the gap between classroom knowledge and practical engineering. Using CampusCart, a running e-commerce database, the book takes you from relational fundamentals, keys, ER modeling, and normalization to advanced SQL, indexing, query optimization, transactions, and recovery. It then explores replication, sharding, distributed transactions, CAP, NoSQL, vector search, and databases for AI.Designed for hands-on preparation, it includes 100 SQL interview problems, ten worked normalization exercises, 177 answer cards, five complete system-design case studies, and six realistic mock interviews with scoring guidance. Cheat sheets and a structured 30-day interview roadmap help turn complex topics into confident, clear answers.Examples use PostgreSQL and MySQL, with practical explanations of performance, security, and production troubleshooting. Whether you are a computer science student, a recent graduate, or a backend or data engineer preparing for your next opportunity, this book helps you move beyond knowing database terminology to understanding how databases work, why design choices matter, and how to explain them under demanding real-world technical interview pressure.