Transaction control statements are used to manage and control the execution of database transactions. A transaction is a logical unit of work that consists of one or more SQL statements. Transaction control statements allow you to ensure data integrity and consistency by defining a set of operations that should be treated as a single atomic operation. The main transaction control statements are:
- BEGIN TRANSACTION,
- COMMIT, and
- ROLLBACK.
BEGIN TRANSACTION
The BEGIN TRANSACTION statement marks the beginning of a transaction. It sets a starting point for a sequence of SQL statements that should be executed as a single unit. The BEGIN TRANSACTION statement is often followed by other SQL statements that make up the transaction.
BEGIN TRANSACTION;
-- SQL statements hereCOMMIT
The COMMIT statement is used to permanently save the changes made within a transaction to the database. It signifies the successful completion of the transaction, and all the changes made within the transaction are permanently applied to the database.
COMMIT;Once the COMMIT statement is executed, the changes made within the transaction are permanently saved.
ROLLBACK
The ROLLBACK statement is used to undo the changes made within a transaction and restore the database to its state before the transaction started. It is typically used when an error or an exceptional condition occurs during the execution of a transaction, allowing you to revert the changes and maintain data consistency.
ROLLBACK;If ROLLBACK statement is executed, all the changes made within the transaction are undone, and the database is reverted to its state before the transaction started.
Transaction control statements are particularly useful in scenarios where multiple SQL statements need to be executed together as an atomic operation. By wrapping these statements within a transaction, you can ensure that all changes are applied together or rolled back as a single unit, maintaining data integrity.
Understanding and utilizing transaction control statements like BEGIN TRANSACTION, COMMIT, and ROLLBACK, allow you to manage database transactions effectively and ensure data consistency and integrity within your SQL operations.