The main function of rollback statement in sql

The ROLLBACK statement can undo all changes in the current transaction and restore it to the state at the beginning of the transaction. Specific operations include: canceling uncommitted data operations, restoring the original values ​​of modified records, and releasing transaction-locked resources. Use ROLLBACK when an error occurs in a transaction, the user wants to undo changes, or the database needs to be rolled back. It should be noted that ROLLBACK cannot undo DDL operations and can only affect the current transaction. Uncommitted changes will be lost after execution.

The main function of ROLLBACK statement in SQL

ROLLBACK is a transaction control statement in SQL. Its main function is Undo all changes made in the current transaction, reverting to the state of the data before the transaction started. ROLLBACK can be performed when an unexpected error occurs in a transaction or when the user wishes to undo changes made.

How ROLLBACK works

The ROLLBACK statement rolls back all data operations performed in the current transaction and releases all resources locked by the transaction. Specifically, it does the following:

• Cancels all uncommitted INSERT, UPDATE, and DELETE operations.
• Restore the original values ​​of all modified records.
• Release all locks held by the transaction.

When to use ROLLBACK

Usually you need to use ROLLBACK in the following situations:

• An error occurs in the transaction: If an error occurs during transaction processing, you can execute ROLLBACK to undo all changes and restore to the state at the beginning of the transaction.
• The user wishes to undo the changes: If the user makes a mistake or changes his mind during the transaction, he can execute ROLLBACK to cancel the changes.
• The database needs to be rolled back: If the database encounters a failure or needs to be restored to a backup, all transactions can be restored to a consistent state by executing ROLLBACK.

Notes

Need to pay attention to the following:

• ROLLBACK cannot undo DDL (data definition language) operations such as create table or drop the index.
• ROLLBACK can only undo changes in the current transaction and cannot affect other transactions.
• After executing ROLLBACK, all uncommitted changes will be lost and cannot be recovered.

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