Which property ensures that a transaction leaves the database in a valid state after it commits?

Which property ensures that a transaction leaves the database in a valid state after it commits?

• A. Consistency
• B. Atomicity
• C. Isolation
• D. Durability

Answer: (A)

Consistency ensures that a transaction leaves the database in a valid state by enforcing all integrity constraints and invariants. When a transaction commits, the data must satisfy rules like primary keys, foreign keys, and check constraints, so the overall state remains valid. If a transaction would violate any constraint, it won’t commit, keeping the database in a correct state. Atomicity is about all-or-nothing execution, isolation about non-interference during concurrent operations, and durability about persisting committed changes even after failures.

Consistency ensures that a transaction leaves the database in a valid state by enforcing all integrity constraints and invariants. When a transaction commits, the data must satisfy rules like primary keys, foreign keys, and check constraints, so the overall state remains valid. If a transaction would violate any constraint, it won’t commit, keeping the database in a correct state. Atomicity is about all-or-nothing execution, isolation about non-interference during concurrent operations, and durability about persisting committed changes even after failures.