When does mysql use transactions?

Mysql uses transactions: 1. Multiple operations need to be consistent. These operations need to be dependent on each other. It is best to include them in a transaction. If one operation fails, the data will return to the original state; 2 , High concurrency environment, multiple users may access and modify the same data at the same time. To ensure the correctness of the data, transactions can be used to isolate each user's operations; 3. Database consistency, some operations will affect multiple tables or multiple Data records, if an operation error occurs, it may cause database inconsistency.

The operating system of this tutorial: Windows 10 system, mysql version 8.0, Dell G3 computer.

MySQL is a powerful relational database management system, and transactions are an important concept and function in MySQL. A transaction is a mechanism used to ensure that a set of related database operations either all execute successfully or none at all.

A transaction is a logical processing unit in the database. It can contain one or more database operations, which can be inserting, updating, or deleting data, etc. Transactions have the following four characteristics (often called ACID):

1. Atomicity: All operations in a transaction are either completed or not executed. If one of the operations fails, the entire transaction is rolled back to its original state.

2. Consistency : The state of the database must remain consistent before and after transaction execution. If the transaction executes successfully, the database should transition from one consistent state to another consistent state.

3. Isolation : The execution of transactions should be isolated from each other and not interfere with each other. Transactions cannot see each other's operations and data changes.

4. Durability (Durability) : Once the transaction is successfully committed, the changes will be permanently saved in the database and will not be lost even if a system failure occurs.

So, when should we use transactions?

1. Multiple operations need to be consistent: When we need to perform a series of operations that depend on each other or need to be consistent, it is best to include them in a transaction. This way, if one of the operations fails, we can roll back the data to its original state.

2. High concurrency environment: In a high concurrency database environment, multiple users may access and modify the same data at the same time. In order to ensure the correctness of data, we can use transactions to isolate each user's operations.

3. Database consistency: Some operations may affect multiple tables or multiple data records. If errors occur in these operations, it may cause database inconsistency. Wrapping these operations into a transaction ensures database consistency.

In MySQL, using transactions can be achieved using the following four keywords: START TRANSACTION (or BEGIN), COMMIT, ROLLBACK and SAVEPOINT.

For example, the following code demonstrates how to use transactions in MySQL:

START TRANSACTION;
INSERT INTO table1 (column1) VALUES (value1);
UPDATE table2 SET column2 = value2 WHERE column3 = value3;
DELETE FROM table3 WHERE column4 = value4;
COMMIT;

In summary, transactions are a very important concept and function in MySQL. By using transactions, we can guarantee that a set of related database operations will either all execute successfully or none at all. This is important to ensure data integrity and consistency. Whether in the case of multi-operation dependencies and consistency, or in high-concurrency environments, it is recommended to use transactions to ensure the correctness of the database.

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