MySQL transaction-ROLLBACK, detailed explanation of COMMIT usage
USE ROLLBACK
Now that we already know what transaction processing is, let’s discuss the issues involved in transaction management.
The key to managing transaction processing is to break down groups of SQL statements into logical chunks and clearly specify when data should and should not be rolled back.
MySQL uses the following statement to identify the start of a transaction:
Input:
start transaction
MySQL's ROLLBACK command is used to roll back (undo) the MySQL statement, please see the following statement :
Input:
select * from ordertotals; start transaction; delete from ordertotals; select * from ordertotals; rollback; select * from ordertotals;
Analysis: This example starts by displaying the contents of the ordertotals table. First execute a SELECT to show that the table is not empty. Then start a transaction and delete all rows in ordertotals with a DELETE statement. Another SELECT statement verifies that ordertotals is indeed empty. At this time, a ROLLBACK statement is used to roll back all statements after START TRANSACTION, and the last SELECT statement shows that the table is not empty.
Obviously, ROLLBACK can only be used within a transaction (after executing a START TRANSACTION command).
Which statements can be rolled back? Transactions are used to manage INSERT, UPDATE, and DELETE statements. You cannot roll back a SELECT statement. (There's little point in doing this either.) You can't roll back a CREATE or DROP operation. These two statements can be used within a transaction block, but they will not be undone if you perform a rollback.
Using COMMIT
General MySQL statements are executed and written directly against the database table. This is the so-called implicit commit, that is, the commit (write or save) operation is performed automatically. However, within a transaction block, commits do not occur implicitly. To make an explicit commit, use the COMMIT statement as follows:
Input:
start transaction; delete from orderitems where order_num = 20010; delete from orders where order_num = 20010; commit;
Analysis: In this example, order 20010 is completely removed from the system. Because it involves updating two database tables, orders and orderItems, a transaction block is used to ensure that orders are not partially deleted. The final COMMIT statement only writes out the changes without error. If the first DELETE works but the second fails, the DELETE is not committed (in fact, it is automatically revoked).
Implicit transaction closure When the COMMIT or ROLLBACK statement is executed, the transaction is automatically closed (future changes will be implicitly committed).
【Related recommendations】
2. MySQL transaction processing example explanation
3. MySQL UPDATE trigger (update) and trigger in-depth analysis
4. MySQL delete trigger (delete) usage detailed explanation
5. Detailed explanation of insert trigger (insert) in MySQL
The above is the detailed content of MySQL transaction-ROLLBACK, detailed explanation of COMMIT usage. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1657
14
1415
52
1309
25
1257
29
1229
24
MySQL's Role: Databases in Web Applications
Apr 17, 2025 am 12:23 AM
The main role of MySQL in web applications is to store and manage data. 1.MySQL efficiently processes user information, product catalogs, transaction records and other data. 2. Through SQL query, developers can extract information from the database to generate dynamic content. 3.MySQL works based on the client-server model to ensure acceptable query speed.
How to start mysql by docker
Apr 15, 2025 pm 12:09 PM
The process of starting MySQL in Docker consists of the following steps: Pull the MySQL image to create and start the container, set the root user password, and map the port verification connection Create the database and the user grants all permissions to the database
Laravel Introduction Example
Apr 18, 2025 pm 12:45 PM
Laravel is a PHP framework for easy building of web applications. It provides a range of powerful features including: Installation: Install the Laravel CLI globally with Composer and create applications in the project directory. Routing: Define the relationship between the URL and the handler in routes/web.php. View: Create a view in resources/views to render the application's interface. Database Integration: Provides out-of-the-box integration with databases such as MySQL and uses migration to create and modify tables. Model and Controller: The model represents the database entity and the controller processes HTTP requests.
Solve database connection problem: a practical case of using minii/db library
Apr 18, 2025 am 07:09 AM
I encountered a tricky problem when developing a small application: the need to quickly integrate a lightweight database operation library. After trying multiple libraries, I found that they either have too much functionality or are not very compatible. Eventually, I found minii/db, a simplified version based on Yii2 that solved my problem perfectly.
Laravel framework installation method
Apr 18, 2025 pm 12:54 PM
Article summary: This article provides detailed step-by-step instructions to guide readers on how to easily install the Laravel framework. Laravel is a powerful PHP framework that speeds up the development process of web applications. This tutorial covers the installation process from system requirements to configuring databases and setting up routing. By following these steps, readers can quickly and efficiently lay a solid foundation for their Laravel project.
MySQL and phpMyAdmin: Core Features and Functions
Apr 22, 2025 am 12:12 AM
MySQL and phpMyAdmin are powerful database management tools. 1) MySQL is used to create databases and tables, and to execute DML and SQL queries. 2) phpMyAdmin provides an intuitive interface for database management, table structure management, data operations and user permission management.
MySQL vs. Other Programming Languages: A Comparison
Apr 19, 2025 am 12:22 AM
Compared with other programming languages, MySQL is mainly used to store and manage data, while other languages such as Python, Java, and C are used for logical processing and application development. MySQL is known for its high performance, scalability and cross-platform support, suitable for data management needs, while other languages have advantages in their respective fields such as data analytics, enterprise applications, and system programming.
MySQL vs. Other Databases: Comparing the Options
Apr 15, 2025 am 12:08 AM
MySQL is suitable for web applications and content management systems and is popular for its open source, high performance and ease of use. 1) Compared with PostgreSQL, MySQL performs better in simple queries and high concurrent read operations. 2) Compared with Oracle, MySQL is more popular among small and medium-sized enterprises because of its open source and low cost. 3) Compared with Microsoft SQL Server, MySQL is more suitable for cross-platform applications. 4) Unlike MongoDB, MySQL is more suitable for structured data and transaction processing.
