Transactions and ACID Properties

What is a Transaction?

A transaction is a unit of work that is either fully completed or fully rolled back.

ACID Properties:

• Atomicity: All operations succeed or none
• Consistency: Database remains valid before and after
• Isolation: Transactions don't interfere
• Durability: Once committed, it stays

Example:

BEGIN;
UPDATE accounts SET balance = balance - 100 WHERE id = 1;
UPDATE accounts SET balance = balance + 100 WHERE id = 2;
COMMIT;