What should I do if mysql displays garbled characters?

MySQL is a popular relational database management system widely used in web applications and other data-driven applications. In the process of using MySQL, garbled characters sometimes occur, that is, the data in the database is displayed as garbled characters or garbled characters are seen in the data files exported from the database. This article will discuss how to solve the problem of MySQL displaying garbled characters.

1. Confirm character set settings

The main cause of garbled characters is character set mismatch. In MySQL, there are two common character sets: server character set and client character set. The server character set is the character set used to store and process data, while the client character set is the character set used for input and output through client connections.

If the server character set and the client character set are different, garbled characters will result. Therefore, we need to check and match them. You can set the server's character set in the MySQL configuration file my.cnf, for example:

[client]
default-character-set=utf8mb4

[mysql]
default -character-set=utf8mb4

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

In this example, both character set and collation are Set to utf8mb4. If you are not sure what character set you should use, it is recommended to use utf8mb4 as it can support a wider range of characters, including emojis.

2. Change database encoding

If the data in the database already exists and the character set is set correctly, but garbled characters are still displayed, you need to change the database encoding. It can be changed through the following steps:

(1) Back up the database

Before making changes, be sure to back up the database to prevent data loss.

(2) Modify the character set and collation of the table

You can modify the character set and collation of the table through the ALTER TABLE statement. For example:

ALTER TABLE tablename CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

This will change the character set and collation of every column in the table to utf8mb4 and utf8mb4_unicode_ci.

(3) Modify the character set and collation rules of the database

After executing the ALTER TABLE statement, you also need to change the character set and collation rules of the database. This can be changed using the following statement:

ALTER DATABASE databasename CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

This will change both the character set and collation of the database to utf8mb4 and utf8mb4_unicode_ci.

(4) Re-import the backup data

After changing the character set and collation rules, the backup data needs to be re-imported into the database.

3. Change the client character set

If the client character set used is incorrect, it will also cause garbled characters. You can change the client character set through the following steps:

(1) Open the MySQL client

Before opening the MySQL client, you need to set the client character set. You can use the following command to open the client and set the character set:

mysql --default-character-set=utf8mb4 -u username -p

(2) Change the client character set

In the client, you can change the client character set using the following command:

SET NAMES utf8mb4;

This will change the client character set to utf8mb4.

4. Other solutions

If none of the above solutions can solve the garbled code problem, you can consider the following solutions:

(1) Use binary to store data

You can consider using binary to store data, which can avoid character set problems. However, this method takes up more storage space and is more complex to operate.

(2) Use Unicode transcoding tool

You can use Unicode transcoding tool to convert garbled characters into correct characters. However, this method is less reliable and may result in data loss or errors.

In short, the garbled character problem is a common problem in MySQL, but it can be solved by setting the correct character set and changing the database encoding. If that still doesn't solve the problem, you can consider other solutions. When using MySQL, it is recommended to understand and learn knowledge related to character sets to effectively avoid garbled characters.

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