ACID Transactions
Transactions group multiple changes into a single unit of work. If anything fails, you can roll back to keep data consistent.
BEGIN;
UPDATE accounts SET balance = balance - 100 WHERE id = 1;
UPDATE accounts SET balance = balance + 100 WHERE id = 2;
COMMIT;Isolation Levels
- • Read Committed (default)
- • Repeatable Read
- • Serializable (strongest)
Row Locks
SELECT * FROM accounts
WHERE id = 1
FOR UPDATE;Locks prevent other transactions from changing the same rows while you update them.