首先， show variables like 'char%';來檢查字符集：
+--------------------------+----------------------------+
| Variable_name | Value |
+--------------------------+----------------------------+
| character_set_client | latin1 |
| character_set_connection | latin1 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | latin1 |
| character_set_server | utf8 |
| character_set_system | utf8 |
其次，修改方式有兩個：
第一種，單次有效，直接在mysql命令行輸入：set names 'utf8';
第二種，永久有效，在my.cnf配置：
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
default-character-set=utf8
[mysql.server]
default-character-set=utf8
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
default-character-set=utf8
[client]
default-character-set=utf8
原理講解：
mysql內部會有多次字符集的轉換：
第一次mysql客戶端到mysql connection的轉換，第二次mysql connection到mysql server的轉換；
所有上面第一張表的Variable_name經過那兩種配置方式後，就變成了：
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 |