1. Character set overview
The character set in MySQL is a standard used to represent text character encoding, which specifies the binary data corresponding to each character. Commonly used character sets provided by MySQL include UTF-8, GBK, GB2312, etc. Under different character sets, the storage space and representation methods occupied by the same character are also different.
2. MySQL character set type
MySQL has support for multiple character set types, including server default, database default, table default, column character set, etc. Among them, the server default character set affects the character set type of MySQL's new database; the database default character set affects the character set type of MySQL's new table; the table default character set affects the character set type of MySQL's new column; and column characters Set is the character set type that directly affects the data storage of a certain column.
3. MySQL character set setting method
The following will introduce the methods and steps of MySQL character set setting:
1. Modify the MySQL configuration file my.cnf
Open the MySQL configuration file my.cnf, find the [mysqld] section, and add the following configuration information:
[mysqld]
character-set-server=utf8
where , character-set-server represents the default character set name of the MySQL server. You can choose different character set types according to your own needs. After saving and closing the my.cnf file, you need to restart the MySQL service for the settings to take effect.
2. Modify the MySQL database character set
If you want to modify the default character set of the database, you can use the following SQL statement:
ALTER DATABASE dbname DEFAULT CHARACTER SET utf8;
Among them, dbname is the name of the database that needs to modify the default character set, and utf8 is the specified character set type.
3. Modify the MySQL table character set
If you want to modify the default character set of a table, you can use the following SQL statement:
ALTER TABLE tablename DEFAULT CHARACTER SET utf8;
Among them, tablename is the name of the table that needs to modify the default character set, and utf8 is the specified character set type.
4. Modify the MySQL column character set
If you want to modify the character set type of a column, you can use the following SQL statement:
ALTER TABLE tablename MODIFY columnname varchar (100) CHARACTER SET utf8;
Among them, tablename is the name of the table whose column character set needs to be modified, columnname is the column name whose character set type needs to be modified, and utf8 is the specified character set type.
4. Common Character Set Problems and Solutions
In the MySQL character set setting, we often encounter some problems, such as garbled characters. Here are some common problems and solutions. Method:
1. Garbled code problem
There are many reasons for the garbled code problem, including the character set of the database, application and connection, etc. Solutions include:
Set the database character set to UTF-8
Set the character set in the application to UTF-8
Set the character set in the connection string to UTF-8
2. Data conversion error
While importing and exporting data , data conversion errors may occur, such as text data containing special characters, etc. Solutions include:
When importing data, set the character set of the data file to be consistent with the character set of MySQL
When exporting data, Use the appropriate UTF-8 format to prevent problems such as garbled characters
3. Character set incompatibility
When the system is upgraded or migrated, the character set may not be compatible Will be affected, for example, the system default character set is incompatible with the MySQL character set. Solutions include:
Before upgrading or migrating, check the compatibility of the character set to ensure that the character set is consistent
Manually modify MySQL characters Set configuration to adapt to the new system character set
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