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Atomicity

Atomicity ensures that all operations within a transaction are completed successfully. If any operation fails, the entire transaction is rolled back. This guarantees that the database remains in a consistent state.


BEGIN TRANSACTION;
  UPDATE accounts SET balance = balance - 100 WHERE account_id = 1;
  UPDATE accounts SET balance = balance + 100 WHERE account_id = 2;
COMMIT;

Console Output:

Transaction completed successfully.

Consistency

Consistency ensures that a transaction can only bring the database from one valid state to another, maintaining database invariants. This means that any data written to the database must be valid according to all defined rules.


CREATE TABLE accounts (
  account_id INT PRIMARY KEY,
  balance DECIMAL CHECK (balance >= 0)
);

Console Output:

Table created with balance check constraint.

Isolation

Isolation ensures that concurrent execution of transactions leaves the database in the same state as if the transactions were executed sequentially. This property is crucial for maintaining consistency in a multi-user environment.


SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;

Console Output:

Transaction isolation level set to SERIALIZABLE.

Durability

Durability ensures that once a transaction has been committed, it will remain so, even in the event of a system failure. This is typically achieved through the use of transaction logs and backups.


BACKUP DATABASE myDatabase TO DISK = 'backup.bak';

Console Output:

Database backup completed successfully.

Transaction Management

Transaction management in databases involves ensuring that the ACID properties are maintained throughout the lifecycle of a transaction. This includes handling transaction failures and ensuring data integrity.


BEGIN TRANSACTION;
  -- SQL operations
ROLLBACK;

Console Output:

Transaction rolled back due to an error.

Concurrency Control

Concurrency control in databases is crucial for ensuring that transactions are processed reliably in a multi-user environment. It involves mechanisms like locking and timestamping to manage simultaneous operations without conflict.


LOCK TABLES accounts WRITE;

Console Output:

Table locked for write operations.

Error Handling

Error handling in transactions is essential for maintaining data integrity. It involves detecting errors during transaction execution and taking appropriate actions, such as rolling back the transaction to maintain consistency.


BEGIN TRY
  BEGIN TRANSACTION;
    -- SQL operations
  COMMIT;
END TRY
BEGIN CATCH
  ROLLBACK;
END CATCH;

Console Output:

Transaction completed or rolled back based on error detection.

Recovery Management

Recovery management ensures that the database can be restored to a consistent state after a failure. This involves using logs and backups to recover lost data and maintain the ACID properties.


RESTORE DATABASE myDatabase FROM DISK = 'backup.bak';

Console Output:

Database restored successfully from backup.