lc_time_names 系统变量指定的区域设置控制用于显示星期和月份名称及其缩写的语言。该变量会影响 DATE_FORMAT()、DAYNAME() 和 MONTHNAME() 函数的输出。The locale indicated by the lc_time_names system variable controls the language used to display day and month names and abbreviations. This variable affects the output from the DATE_FORMAT(), DAYNAME(), and MONTHNAME() functions.

lc_time_names 不会影响 STR_TO_DATE() 或 GET_FORMAT() 函数。lc_time_names does not affect the STR_TO_DATE() or GET_FORMAT() function.

lc_time_names 的值不会影响 FORMAT() 的结果，但该函数接受一个可选的第三个参数，用于指定用于结果数字的十进制点、千位分隔符以及分隔符之间分组的区域设置。允许的区域设置值与 lc_time_names 系统变量的合法值相同。The lc_time_names value does not affect the result from FORMAT(), but this function takes an optional third parameter that enables a locale to be specified to be used for the result number's decimal point, thousands separator, and grouping between separators. Permissible locale values are the same as the legal values for the lc_time_names system variable.

区域名称具有由 IANA 列出的语言和地区子标签（http://www.iana.org/assignments/language-subtag-registry），例如 'ja_JP' 或 'pt_BR'。默认值是 'en_US'，不管您的系统区域设置如何，但您可以在服务器启动时设置该值，或者如果您有足够权限设置全局系统变量，也可以在运行时设置 GLOBAL 值；参见 第 7.1.9.1 节，“系统变量权限”。任何客户端都可以查看 lc_time_names 的值，或者设置其 SESSION 值以影响自身连接的区域设置。Locale names have language and region subtags listed by IANA (http://www.iana.org/assignments/language-subtag-registry) such as 'ja_JP' or 'pt_BR'. The default value is 'en_US' regardless of your system's locale setting, but you can set the value at server startup, or set the GLOBAL value at runtime if you have privileges sufficient to set global system variables; see Section 7.1.9.1, “System Variable Privileges”. Any client can examine the value of lc_time_names or set its SESSION value to affect the locale for its own connection.

（下面示例中的第一个 SET NAMES 语句可能不是必需的，如果没有修改与字符集和排序规则相关的设置；我们为了完整性将其包括在内。）(The first SET NAMES statement in the following example may not be necessary if no settings relating to character set and collation have been changed from their defaults; we include it for completeness.)

mysql> SET NAMES 'utf8mb4';
Query OK, 0 rows affected (0.09 sec)

mysql> SELECT @@lc_time_names;
+-----------------+
| @@lc_time_names |
+-----------------+
| en_US           |
+-----------------+
1 row in set (0.00 sec)

mysql> SELECT DAYNAME('2020-01-01'), MONTHNAME('2020-01-01');
+-----------------------+-------------------------+
| DAYNAME('2020-01-01') | MONTHNAME('2020-01-01') |
+-----------------------+-------------------------+
| Wednesday             | January                 |
+-----------------------+-------------------------+
1 row in set (0.00 sec)

mysql> SELECT DATE_FORMAT('2020-01-01','%W %a %M %b');
+-----------------------------------------+
| DATE_FORMAT('2020-01-01','%W %a %M %b') |
+-----------------------------------------+
| Wednesday Wed January Jan               |
+-----------------------------------------+
1 row in set (0.00 sec)

mysql> SET lc_time_names = 'es_MX';
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT @@lc_time_names;
+-----------------+
| @@lc_time_names |
+-----------------+
| es_MX           |
+-----------------+
1 row in set (0.00 sec)

mysql> SELECT DAYNAME('2020-01-01'), MONTHNAME('2020-01-01');
+-----------------------+-------------------------+
| DAYNAME('2020-01-01') | MONTHNAME('2020-01-01') |
+-----------------------+-------------------------+
| miércoles             | enero                   |
+-----------------------+-------------------------+
1 row in set (0.00 sec)

mysql> SELECT DATE_FORMAT('2020-01-01','%W %a %M %b');
+-----------------------------------------+
| DATE_FORMAT('2020-01-01','%W %a %M %b') |
+-----------------------------------------+
| miércoles mié enero ene                 |
+-----------------------------------------+
1 row in set (0.00 sec)

每个受影响函数的日期或月份名称将从 utf8mb4 转换为由 character_set_connection 系统变量指定的字符集。The day or month name for each of the affected functions is converted from utf8mb4 to the character set indicated by the character_set_connection system variable.

lc_time_names 可以设置为以下任何区域设置值。MySQL 支持的区域设置集合可能与您的操作系统支持的有所不同。lc_time_names may be set to any of the following locale values. The set of locales supported by MySQL may differ from those supported by your operating system.