apt-get install 安装的，不是源码包安装的mysql

1 修改mysql的配置文件

/etc/mysql/conf.d/mysql.cnf

在[mysql]的下方加入如下语句:(注：这个文件下没有配置，只有【mysql】)

no-auto-rehash
default-character-set=utf8

/etc/mysql/mysql.conf.d/mysqld.cnf

在[mysqld]下加入

socket = /var/run/mysqld/mysqld.sock
port = 3306
character-set-server=utf8 （这里是server，之前有的版本是set）

重启mysql: sudo /etc/init.d/mysql restart

查看字符集

mysql> 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)

设置之后如果之前的数据库已经创建了，只能删除重新创建了。