修改mysql的配置文件,使数据库与服务器操作系统的字符集设置一致。
    vi /etc/my.cnf 设置(如果没有发现这个文件，就新建1个)
    [mysqld]
    datadir=/var/lib/mysql
    socket=/var/lib/mysql/mysql.sock
    default-character-set=utf8  (增加的关键一句,使得数据库缺省以utf8存储)
    当然，修改后，要重启数据库。
    
    再次用mysql -u root -p命令进入数据库系统，用SHOW VARIABLES LIKE 'character_set_%';命令查看到如下内容：
+--------------------------+-----------------------------------------------------------------------+
| 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                                                                  | 
| character_sets_dir       | /usr/local/mysql-5.1.20-beta-linux-i686-glibc23/share/mysql/charsets/ | 
+--------------------------+-----------------------------------------------------------------------+
    发现关键项目已经用了utf8，但这样还不够，还要保证客户端也是用utf8的字符集来操作的。
    登录的时候，要用以下命令：mysql --default-character-set=utf8 -u root -p
   
    再次用SHOW VARIABLES LIKE 'character_set_%';命令查看，结果变成了：
+--------------------------+-----------------------------------------------------------------------+
| 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/local/mysql-5.1.20-beta-linux-i686-glibc23/share/mysql/charsets/ | 
+--------------------------+-----------------------------------------------------------------------+
    这样才能保证客户端所发命令都是基于utf8格式的，比如说建立数据库和表，默认就会以utf8编码，而无须再次指定。

需要说明一下，如果在修改编码之前已经建好数据库，需要删掉原来，重新建立数据库。