字符集和排序规则在四个层级上有默认设置：服务器、数据库、表和列。以下各节中的描述可能看起来复杂，但实践中发现，多层级的默认设置会产生自然且明显的结果。There are default settings for character sets and collations at four levels: server, database, table, and column. The description in the following sections may appear complex, but it has been found in practice that multiple-level defaulting leads to natural and obvious results.

CHARACTER SET 用于指定字符集的子句中。CHARSET 可以作为 CHARACTER SET 的同义词使用。CHARACTER SET is used in clauses that specify a character set. CHARSET can be used as a synonym for CHARACTER SET.

字符集问题不仅影响数据存储，还会影响客户端程序与 MySQL 服务器之间的通信。如果希望客户端程序使用不同于默认的字符集与服务器进行通信，需要指明所使用的字符集。例如，要使用 latin1 Unicode 字符集，在连接服务器后执行以下语句：Character set issues affect not only data storage, but also communication between client programs and the MySQL server. If you want the client program to communicate with the server using a character set different from the default, you need to indicate which one. For example, to use the latin1 Unicode character set, issue this statement after connecting to the server:

SET NAMES 'latin1';

有关客户端/服务器通信中字符集相关问题的更多信息，请参见 第 12.4 节，“连接字符集和排序规则”。For more information about character set-related issues in client/server communication, see Section 12.4, “Connection Character Sets and Collations”.