mysql utf8 garbled code

With the development of the Internet, the amount of data is becoming larger and larger. Therefore, in order to facilitate the storage and access of data, databases came into being. However, when using the MySQL database, you may encounter some problems, such as garbled characters in the utf8 character set. How to solve this problem? This article will explore this issue in detail.

1. What is the utf8 character set

Before we start to solve the garbled problem of the utf8 character set, we must first understand what the utf8 character set is. UTF-8 is a variable-length character encoding for Unicode and a variable-width character set. It can use one to four bytes to represent a Unicode character, with a maximum number of characters of 0x10FFFF. Due to its flexibility and backward compatibility, UTF-8 is currently one of the most commonly used character encodings for network transmission and storage.

2. The reason why the utf8 character set is garbled

1. MySQL character set setting

When using the MySQL database, you need to set the character set in advance. If the character set is set incorrectly, garbled characters will appear during data transmission. Normally, we can set the character set in the MySQL configuration file my.cnf.

2. Character set settings for databases and data tables

When creating a database or data table, you also need to set the corresponding character set. If the character set of the database or data table is incorrectly set, it will cause garbled characters during data transmission. Normally, we can modify the character set of the database or data table through the commands ALTER DATABASE and ALTER TABLE.

3. Character sets are inconsistent between the application and the database

Sometimes, when character sets are converted between the application and the database, data transmission will also occur. Garbled code problems occur. For example, if the application uses the utf-8 character set and the database uses the gb2312 character set, garbled characters may occur.

4. Problems with the database driver

If there is a problem with the MySQL driver, it will also cause the utf-8 character set garbled problem. To avoid this situation, we should choose a suitable MySQL driver.

3. Methods to solve the problem of utf8 character set garbled characters

1. Modify the character set of MySQL

If the character set of MySQL is not set correctly, we can Solved by modifying the my.cnf configuration file. Specifically, we can add the following content to the my.cnf configuration file:

[client]
default-character-set=utf8mb4

[mysql]
default-character-set=utf8mb4

[mysqld]
character-set-server=utf8mb4
collation-server=utf8mb4_unicode_ci

The above configuration items can set the MySQL client character set, the MySQL default character set, and the MySQL server character set.

After modifying the my.cnf configuration file, you need to restart the MySQL service for the modification to take effect.

2. Modify the character set of the database and data table

If the character set of the created database or data table is incorrect, we can use the ALTER DATABASE and ALTER TABLE commands. to modify.

For example, to change the character set of the database to utf8mb4, you can use the following command:

ALTER DATABASE 数据库名 CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

It is also similar to modify the character set of the data table:

ALTER TABLE 表名 CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

The above command will The character set of the specified data table will be modified to utf8mb4. Note that COLLATE needs to be specified, otherwise MySQL will use the default comparison rules.

3. Modify the character set between the application and the database

When the character set used by the application is inconsistent with the database, we can solve the problem by setting the encoding when connecting to MySQL . For example, when using PDO to connect to the MySQL database, you can use the following code:

$dsn = 'mysql:host=localhost;dbname=test';
$username = 'username';
$password = 'password';
$options = [PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES 'utf8mb4'"];
$pdo = new PDO($dsn, $username, $password, $options);

In the $options parameter, set PDO::MYSQL_ATTR_INIT_COMMAND to "SET NAMES 'utf8mb4'", which means that when connecting to MySQL, set The character set is utf8mb4.

4. Use the correct database driver

In order to avoid problems with the MySQL driver, we should choose the appropriate MySQL driver. For example, when using PHP to connect to a MySQL database, it is recommended to use the mysqli or PDO_MYSQL extension instead of the mysql extension.

4. Conclusion

It is very common to encounter the problem of garbled characters in the utf8 character set in the MySQL database, but we can easily solve this problem as long as we follow the correct setting method. In the actual development process, we should reasonably choose the character set of MySQL, modify the character set of the database and data table, use the correct database driver, etc., to ensure the correctness and integrity of data transmission.

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