Transactions

SQL transactions provide a way to group multiple SQL operations into a single, atomic unit of work. A transaction ensures that either all operations within it are successfully completed (committed) or none of them are (rolled back), maintaining data integrity and consistency. Let's delve into SQL transactions with examples and key concepts.

 

ACID Properties:

Atomicity: Ensures that all operations within a transaction are completed successfully or none at all. If any part of the transaction fails, the entire transaction is rolled back to its initial state.

Consistency: Guarantees that the database remains in a consistent state before and after the transaction. Constraints, triggers, and cascades ensure data validity.

Isolation: Ensures that transactions are isolated from each other until they are completed. Concurrent transactions should not interfere with each other.

Durability: Once a transaction is committed, its changes are permanent even in the event of system failures.

 

Transaction Commands:

BEGIN TRANSACTION: Begins a new transaction explicitly.

COMMIT: Finalizes the transaction and makes all changes permanent.

ROLLBACK: Aborts the transaction and undoes any changes made since the transaction began.

SAVEPOINT: Creates a point within the transaction to which you can roll back.