A transaction is a sequence of one or more SQL operations that are executed as a single unit of work. Transactions have four key properties, often referred to as ACID:
- Atomicity: Ensures that all operations within a transaction are completed successfully; if any operation fails, the entire transaction is rolled back.
- Consistency: Guarantees that a transaction will bring the database from one valid state to another, maintaining data integrity.
- Isolation: Ensures that the operations within a transaction are invisible to other transactions until the transaction is committed.
- Durability: Once a transaction is committed, its changes are permanent, even in the event of a system failure.