修改字符集有两种方法：
（1）编辑 vim /etc/my.cnf 配置文件，在相应段中加入相应的参数字符集，修改完毕后，重启 MySQL 服务务即可

[root@localhost ~]# vim /etc/my.cnf
[mysqld]
character-set-server=utf8
[client]
default-character-set=utf8
[mysql]
default-character-set=utf8
[root@localhost ~]# systemctl restart mariadb.service
[root@localhost ~]# mysql
MariaDB [(none)]> show variables like '%char%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | utf8                       |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | utf8                       |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)

（2）MySQL 命令行中运行如下指令

MariaDB [(none)]> SET character_set_client = utf8; 
MariaDB [(none)]> SET character_set_results = utf8; 
MariaDB [(none)]> SET character_set_connection = utf8;
MariaDB [(none)]> show variables like '%char%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | utf8                       |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | utf8                       |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)