ACID Guarantees & Transaction Control (BEGIN, COMMIT, ROLLBACK)
Understand Atomicity, Consistency, Isolation, Durability (ACID), transaction isolation levels, and concurrency locking.
ACID Guarantee Invariants
### The ACID Model
- **Atomicity**: All-or-nothing execution. If any operation fails, the entire transaction is rolled back.
- **Consistency**: Database transitions strictly from one valid state conforming to schema invariants to another.
- **Isolation**: Concurrent transactions execute independently without dirty reads or phantom reads.
- **Durability**: Committed transaction data persists permanently even during hardware power failure.
