问题
Windows 下安装 MySQL 后，默认编码不全utf8。
mysql> show variables like '%char%';
+--------------------------+---------------------------------------------------------+
| Variable_name | Value |
+--------------------------+---------------------------------------------------------+
| character_set_client | gbk |
| character_set_connection | gbk |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | gbk |
| character_set_server | utf8 |
| character_set_system | utf8 |
| character_sets_dir | D:\Program Files\MySQL\MySQL Server 5.7\share\charsets\ |
+--------------------------+---------------------------------------------------------+
8 rows in set, 1 warning (0.01 sec)
解决方案
进入 MySQL 安装的目录，复制 my-default.ini，重命名为 my.ini，添加如下配置：
[mysqld]
character-set-server = utf8 [client]
default-character-set = utf8
重启 MySQL 服务（右键计算机 > 管理 > 服务和应用程序 > 服务 > MySQL），再次查看确实是否生效。
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 | D:\Program Files\MySQL\MySQL Server 5.7\share\charsets\ |
+--------------------------+---------------------------------------------------------+
8 rows in set, 1 warning (0.01 sec)