PHP PDO connection to MySQL database: How does the charset=utf8 setting affect the database character set?

Understand the character set settings of PHP PDO to connect to MySQL database

When PHP PDO connects to MySQL database, it is crucial to correctly set the character set, which is directly related to the accuracy of data interaction. This article will analyze in detail the role of charset=utf8 parameter in $dsn = 'mysql:host=192.168.111.114;dbname=test;charset=utf8'; and its association with the MySQL server character set settings.

Code snippet $dsn = 'mysql:host=192.168.111.114;dbname=test;charset=utf8'; defines the DSN of the PDO (data source name). charset=utf8 parameter specifies that the connection is encoded using UTF-8. This means that when PHP programs interact with the database, all data transmission and processing will be encoded in UTF-8.

So, what does charset=utf8 have to do with MySQL server character set settings (viewed through show variables LIKE "%char%"; command)? The key is that if charset is specified in the PDO connection string, the connection will force the specified character set, and ignore the default character set of the MySQL server. On the contrary, if charset is not specified in the PDO connection string, the connection will use the default character set of the MySQL server. This can be viewed through show variables LIKE "%char%"; for example, character_set_client , character_set_connection , character_set_database , and character_set_results , respectively, representing the character sets of the client, connection, database and result set. It should be noted that show variables command displays the settings of the current session, not the global settings. Database management tools (such as Navicat) may also send character set settings by themselves, which need to be judged based on the tool configuration.

Therefore, to ensure that the data is encoded correctly, it is best practice to explicitly declare charset parameter in the PDO connection string.

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