Database Transactions: ACID Properties in Plain...

What Is a Transaction? A transaction is a group of database operations that either all succeed or all fail together. BEGIN; UPDATE accounts SET balance = balance - 100 WHERE id = 1; UPDATE accounts SET balance = balance + 100 WHERE id = 2; COMMIT; If the second update fails, the first one rolls back automatically. Money doesn't disappear into the void. ACID: The Four Guarantees Atomicity "All or nothing." BEGIN; INSERT INTO orders (user_id, total) VALUES (42, 9900); INSERT INTO order_items (orde