6 lessons
What is data, and what is a database, really?
Starting from the absolute basics — what data means, why we collect it, and what turns a pile of facts into something a computer can use.
Data models through history — hierarchical, network, relational, and NoSQL
How the way we organize data has evolved, from rigid tree-shaped hierarchical databases to today's relational and NoSQL systems, and why the relational model won for so long.
The problems with file-based systems
Data redundancy, inconsistency, isolation, integrity, atomicity and concurrency problems — the exact failures a DBMS was invented to fix.
What is a DBMS, and what does it actually give you?
Defining a DBMS precisely, and walking through every advantage it provides over raw file storage — with concrete examples for each one.
The three-schema architecture and data independence
How a DBMS separates physical storage, logical structure, and each user's personal view of the data — and why that separation is the key to data independence.
Database languages and the people who use them
DDL, DML, DCL and TCL explained simply, plus the different kinds of users who interact with a database system.