linux下怎么修改mysql的字符集编码

安装完的MySQL的默认字符集为 latin1 ，为了要将其字符集改为用户所需要的(比如utf8)，就必须改其相关的配置文件；由于linux下MySQL的默认安装目录分布在不同的文件下；不像windows一样放在同一目录下，只需修改其中的my.ini文件，重起后就生效了；所以先来看看linux下MySQL的数据库文件、配置文件和命令文件分别在不同的目录 ：
     1、数据库目录，其所创建的数据库文件都在该目录下
　　/var/lib/mysql/

　　 2、配置文件 （mysql.server命令及配置文件所在地）
　　/usr/share/mysql

　　 3、相关命令（如mysql mysqladmin等）
　　/usr/bin

　　 4、启动脚本（如mysql启动命令）
　　/etc/rc.d/init.d/

查看默认字符集
            #mysql -u root - p
            #(输入密码)
            mysql> show variables like 'character_set%' ;//或者是status
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | latin1                     |
| character_set_connection | latin1                     |
| character_set_database   | latin1                     |
| character_set_filesystem | binary                     |
| character_set_results    | latin1                     |
| character_set_server     | latin1                     |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
            修改字符集 ：
         1.查找/etc目录下是否有my.cnf文件；
            #ls -l | grep my.cnf (在/etc下查找是否有my.cnf文件存在)
          2.如果没有就要从/usr/share/mysql,拷贝一个到/etc 下，在/usr/share/mysql目录下有五个后缀为.cnf的文件，分别是 my-huge.cnf    my-innodb-heavy-4G.cnf    my-large.cnf   my-medium.cnf     my-small.cnf ；从中随便拷贝一个到/etc目录下并将其改为my.cnf文件,我选择的是my-medium.cnf ：
           #cp /usr/share/mysql/my-medium.cnf   /etc/my.cnf
          3.修改my.cnf文件，在该文件中的三个地方加上 default-character-set=utf8（[client] [mysqld] [mysql]）
             #vi  /etc/my.cnf
             修改如下：（红色为添加部分）
             [client]
            #password       = your_password
             port            = 3306
             socket          = /var/lib/mysql/mysql.sock
             default-character-set=utf8 
              [mysqld]
               port            = 3306
                socket          = /var/lib/mysql/mysql.sock
                skip-locking
                key_buffer = 16M
                max_allowed_packet = 1M
                table_cache = 64
                sort_buffer_size = 512K
                net_buffer_length = 8K
               read_buffer_size = 256K
               read_rnd_buffer_size = 512K
               myisam_sort_buffer_size = 8M
               default-character-set=utf8
               init_connect='SET NAMES utf8'   //此行可不加

               [mysql]
               no-auto-rehash
               default-character-set=utf8
              保存退出；
           4.重起MySQL服务器，使其设置的内容生效
              #/etc/init.d/mysql  restart
            5. 重新登入mysql；
               # mysql -u root - p
                #(输入密码)
               mysql> show variables like 'character_set%' ;
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |（都生成了utf8，成功了 哈哈哈）
| 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/ |
+--------------------------+----------------------------+

        mysql启动和停止 操作 ：
        可以通过 #/etc/init.d/mysql   [start | stop | restart](实现启动，停止，重启)
        也可以通过 #service mysql [start | stop | restart](实现启动，停止，重启)
*********************************
另外：如果在修改字符集前，尝试在数据库中插入中文，那么当修改了字符集后，在你所插入中文的数据库中（在别的数据库中可能没问题），
通过show variables like 'character_set%'查询的结果可如下：
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | latin1                     |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | utf8                       |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
如图，character_set_database仍然会为latin1，我采取的办法是先导出该数据库中数据，如果数据不重要，则可drop此数据库，
然后再重新create一个数据库。
倘若不行的话，可以用命令行的形式

通过MySQL命令行修改:

mysql> set character_set_client=utf8;Query OK, 0 rows affected (0.00 sec)

mysql> set character_set_connection=utf8;
Query OK, 0 rows affected (0.00 sec)

mysql> set character_set_database=utf8;
Query OK, 0 rows affected (0.00 sec)

mysql> set character_set_results=utf8;
Query OK, 0 rows affected (0.00 sec)

mysql> set character_set_server=utf8;
Query OK, 0 rows affected (0.00 sec)

mysql> set character_set_system=utf8;
Query OK, 0 rows affected (0.01 sec)

mysql> set collation_connection=utf8;
Query OK, 0 rows affected (0.01 sec)

mysql> set collation_database=utf8;
Query OK, 0 rows affected (0.01 sec)

mysql> set collation_server=utf8;
Query OK, 0 rows affected (0.01 sec)

查看:
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/ |
+--------------------------+----------------------------+
8 rows in set (0.03 sec)

mysql> show variables like 'collation_%';
+----------------------+-----------------+
| Variable_name        | Value           |
+----------------------+-----------------+
| collation_connection | utf8_general_ci |
| collation_database   | utf8_general_ci |
| collation_server     | utf8_general_ci |
+----------------------+-----------------+
3 rows in set (0.04 sec)