MySQL database automatic submission mechanism analysis

MySQL database automatic submission mechanism analysis

MySQL is a commonly used open source relational database management system. It adopts a method called automatic submission mechanism. Handle business. In MySQL, the automatic submission mechanism is turned on by default, which means that each SQL statement will be executed immediately and submitted to the database, causing irreversible effects. Understanding MySQL's automatic commit mechanism is very important for developers because it directly affects transaction control and data integrity.

The principle of the automatic submission mechanism is to automatically submit a SQL statement to the database every time it is executed, so that there is no need to manually call the submit command to confirm the operation. This method is very convenient in some cases, such as for some simple query operations. But when it comes to transaction processing, the automatic commit mechanism may cause some problems, such as data inconsistency or operation errors that cannot be rolled back.

In MySQL, you can control the switch of the automatic submission mechanism by setting session variables. You can use the following statement to view the current automatic submission status:

SHOW VARIABLES LIKE 'autocommit';

With this statement we can view the current automatic submission status. If the value is 1, it indicates the automatic submission mechanism. It is turned on. If the value is 0, it means that the automatic submission mechanism is turned off.

To demonstrate the impact of the automatic submission mechanism, we can illustrate it through the following code example:

1. First, create a test table:

CREATE TABLE test_table (
    id INT PRIMARY KEY,
    name VARCHAR(50)
);

2. Then insert a piece of data and query:

INSERT INTO test_table (id, name) VALUES (1, 'Alice');
SELECT * FROM test_table;

If the automatic submission mechanism is turned on, by default these two statements will be executed immediately and submitted to the database. You can verify whether the data is successfully inserted by querying.

3. Then turn off the automatic submission mechanism:

SET autocommit = 0;

4. Then insert a piece of data and query:

INSERT INTO test_table (id, name) VALUES (2, 'Bob');
SELECT * FROM test_table;

When the automatic submission mechanism is turned off, these two statements will not be executed and submitted immediately. You need to manually call the submit command to confirm the operation. Without manual submission, the data will not be inserted into the database.

5. Finally, manually submit the operation:

COMMIT;

By manually submitting the command, the previous insertion operation will take effect, and the verification data can be queried Whether the insertion was successful.

In summary, MySQL's automatic submission mechanism has an important impact on transaction processing. Developers need to flexibly control the automatic submission status according to actual needs to ensure data integrity and consistency. At the same time, understanding the principles and operation methods of the automatic submission mechanism will also help to better handle database operations.

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