Databases: Where every app keeps its truth

A database is the part of the system chosen to survive the crash.

The relational model

Data as typed tables, integrity in constraints, access in declarative SQL. You describe what you want; the planner decides how.

Transactions are promises

ACID: atomicity, consistency, isolation, durability. Together they explain why money transfers never vanish half-completed.

ACID

What this course teaches

Nine units: the relational model, SQL, schema design and normalization, storage and indexing, transactions, query processing, distribution, NoSQL, and modern practice.

Flashcard

A = L + E

Not the accounting equation

Proof that context matters: in databases the sacred identity is the relational model’s keys, not balance sheets.

Check your understanding

The component that keeps the transfer atomic is: