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TCL (Transaction Control Language)

Transaction Control Language (TCL) is a subset of SQL used to manage transactions within a database. TCL commands, such as COMMIT, ROLLBACK, and SAVEPOINT, control the execution and outcome of transactions. These commands ensure data integrity by allowing users to commit or rollback changes made during a transaction, or set savepoints to create checkpoints for potential rollbacks. TCL is essential for maintaining consistency and reliability in database operations.

 

COMMIT: COMMIT is a Transaction Control Language (TCL) command used to permanently save the changes made during a transaction. Here's an example and explanation

BEGIN TRANSACTION; UPDATE employees SET salary = salary * 1.1 WHERE department = 'Sales'; SAVEPOINT before_commit; COMMIT;

In this example, we’re starting a transaction to ensure that the subsequent updates are treated as a single unit of work. We then update the salaries of employees in the 'Sales' department. Before committing the changes permanently, we set a savepoint to which we can rollback if needed. Finally, we commit the transaction, making the changes permanent in the database.


ROLLBACK, SAVEPOINT: ROLLBACK is a Transaction Control Language (TCL) command used to undo changes made during a transaction. Here's an example and explanation.

SAVEPOINT is a Transaction Control Language (TCL) command used to set a named marker within a transaction. Here's an example and explanation:

BEGIN TRANSACTION; UPDATE employees SET salary = salary * 1.1 WHERE department = 'Sales'; SAVEPOINT before_commit; ROLLBACK TO before_commit;

In this example, we're using ROLLBACK TO to rollback the changes made during the transaction to a specific savepoint, undoing any modifications made to the database since that savepoint was set.

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