mysqlの下記のそれぞれの意味を調べる
mysql> show variables like 'character_set%';
+--------------------------+----------------------------+
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/ |
+--------------------------+----------------------------+