Rolling back Actions in Oracle: Undoing Changes and Restoring Database State

Rolling back action in Oracle

Introduction

In Oracle, rolling back an action refers to undoing the changes made by a transaction and restoring the database to its previous state. This article will explain the concept of rolling back actions in Oracle and provide a step-by-step guide on how to perform a rollback.

Understanding Transactions

Before diving into rolling back actions, it is important to understand the concept of transactions in Oracle. A transaction is a logical unit of work that consists of one or more SQL statements. These statements can include data manipulation operations such as insert, update, and delete.

Transactions are crucial in maintaining data integrity and consistency in a database. They ensure that a group of related changes either succeed together or fail together. If a transaction fails or encounters an error, it can be rolled back to undo the changes made so far.

Performing a Rollback

To perform a rollback in Oracle, follow these steps:

1. Connect to the Oracle database using a client tool or command line.
2. Start a transaction by executing the «BEGIN» statement.
3. Execute the desired SQL statements within the transaction.
4. If at any point you want to roll back the changes, execute the «ROLLBACK» statement.
5. If you want to commit the changes and make them permanent, execute the «COMMIT» statement.

Example

Let’s consider an example where we want to update the salary of an employee in the «employees» table but later decide to roll back the changes.

1. Connect to the Oracle database using SQL*Plus.
2. Begin a transaction by executing the command: «BEGIN TRANSACTION;»
3. Update the salary of the employee using the SQL statement: «UPDATE employees SET salary = 5000 WHERE employee_id = 100;»
4. Check the updated salary by executing a SELECT statement.
5. Decide to roll back the changes by executing the command: «ROLLBACK;»
6. Verify that the salary of the employee is restored to its previous value.

Conclusion

Rolling back actions in Oracle allows you to undo changes made by a transaction and restore the database to its previous state. Understanding transactions and how to perform a rollback is essential for maintaining data integrity and recovering from errors. By following the steps outlined in this article, you can easily roll back actions in Oracle and revert any unwanted changes.

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