Database transaction processing skills in MySQL

MySQL is a popular relational database management system. Among them, transaction processing is an essential part of database operations. Transaction processing is the process of putting multiple database operations together and performing them as a single unit. During transaction processing, if an error occurs in any operation, the entire transaction will be rolled back.

In this article, we will discuss database transaction processing techniques in MySQL.

1. Open transaction

In MySQL, you need to use the following command to open a transaction:

START TRANSACTION;

Using this command will open a new transaction and It is placed in active state. Once this command is run, all subsequent MySQL queries will be considered to be performed within a transaction.

2. Commit transaction

When the transaction processing is completed successfully and all SQL statements are executed successfully, you need to use the following command to submit the transaction:

COMMIT;

Use this The command will commit the current transaction and save it permanently changed in the database. After a transaction is committed, MySQL closes all database connections that kept the transaction active.

3. Rollback transaction

If an error occurs during transaction processing, you need to use the following command to roll back the transaction:

ROLLBACK;

Use this command to undo current transaction and revert all changes. After rolling back the transaction, MySQL will close all database connections and set the transaction status to "Rolled Back".

4. Combining multiple operations into one transaction

In MySQL, multiple operations can be combined into one transaction and submitted or rolled back with one statement. For example, the following statement will delete all orders containing item "foo" from the table "orders" and delete all related information in the table "order_details":

START TRANSACTION;
DELETE FROM orders WHERE product_name = 'foo';
DELETE FROM order_details WHERE product_name = 'foo';
COMMIT;

In this example, all operations are Performed within a transaction to ensure that changes are correctly persisted or rolled back.

5. Set automatic submission

By default in MySQL, automatic submission is turned on. This means that every SQL query will be submitted to the database immediately. In order to turn off automatic commit, you need to use the following command:

SET AUTOCOMMIT=0;

After using this command, all SQL queries will remain in the transaction until the transaction is explicitly committed or rolled back. To turn on autocommit again, use the following command:

SET AUTOCOMMIT=1;

6. Avoiding deadlocks

Deadlocks may occur when multiple users access the database at the same time. Deadlock refers to a situation where multiple users are blocked waiting for each other while waiting for other users to release the lock. To avoid deadlocks, try to shorten the duration of each transaction and avoid long waits or locks.

7. Monitoring transactions

In MySQL, you can use the following command to monitor transactions:

SHOW ENGINE INNODB STATUS;

Using this command will display the details of the currently active transactions , including uncommitted transactions and locked objects. This command can help identify transactions that may cause deadlocks or other problems.

In practical applications, the skills of using MySQL to handle transaction processing are very important. The techniques described in this article can help reduce error rates, increase program reliability, and improve system performance. By correctly using MySQL transaction processing techniques, you can ensure data security and improve the reliability of database applications.

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