语法
SET NAMES {'charset_name' [COLLATE 'collation_name'] | DEFAULT}
其中，charset_name和collation_name可不加引号，当用户给出collation_name时，字符序也将被设置为给定值。
示例
mysql> SHOW SESSION VARIABLES LIKE 'character\_set\_%';
+--------------------------+---------+| Variable_name | Value |
+--------------------------+---------+
| character_set_client | utf8mb4 |
| character_set_connection | utf8mb4 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | utf8mb4 |
| character_set_server | utf8 |
| character_set_system | utf8 |
+--------------------------+---------+
7 rows in set (0.03 sec)
mysql> SET NAMES gb18030 COLLATE gb18030_chinese_ci;
Query OK, 0 rows affected (0.02 sec)
mysql> SHOW SESSION VARIABLES LIKE 'character\_set\_%';
+--------------------------+---------+
| Variable_name | Value |
+--------------------------+---------+
| character_set_client | gb18030 |
| character_set_connection | gb18030 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | gb18030 |
| character_set_server | utf8 |
| character_set_system | utf8 |
+--------------------------+---------+
7 rows in set (0.02 sec)
