转载自：http://www.tuicool.com/articles/6b2Qvm
今天在部署一个系统时，网页出现了乱码。于是各种百度（之前一直用同一种方式，但是没影响使用），
下面做个试验。
本服务器系统是centos6.3，lamp环境全部用yum安装。没有优化过任任何配置
下面看mysql默认字符集配置
mysql> show variables like "%char%";
+--------------------------+----------------------------+
| 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/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)
mysql> show variables like 'collation_%';
+----------------------+-------------------+
| Variable_name | Value |
+----------------------+-------------------+
| collation_connection | latin1_swedish_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
+----------------------+-------------------+
3 rows in set (0.00 sec)
mysql > show variables like "%char%" ; +--------------------------+----------------------------+ | 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/ | +--------------------------+----------------------------+ 8 rows in set (0.00 sec) mysql > show variables like 'collation_%' ; +----------------------+-------------------+ | Variable_name | Value | +----------------------+-------------------+ | collation_connection | latin1_swedish_ci | | collation_database | latin1_swedish_ci | | collation_server | latin1_swedish_ci | +----------------------+-------------------+ 3 rows in set (0.00 sec) |
接下来我们建一个数据库
mysql> use test;
Database changed
mysql> CREATE TABLE `test_user` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`username` varchar(255) CHARACTER SET utf8 DEFAULT NULL,
`email` varchar(255) CHARACTER SET utf8 DEFAULT NULL COMMENT 'email',
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COMMENT='测试数据库字符集';
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| test_user |
+----------------+
1 rows in set (0.00 sec)
mysql > use test; Database changed mysql > CREATE TABLE `test_user` ( `id` int (10) unsigned NOT NULL AUTO_INCREMENT , `username` varchar (255) CHARACTER SET utf8 DEFAULT NULL , `email` varchar (255) CHARACTER SET utf8 DEFAULT NULL COMMENT 'email' , PRIMARY KEY (`id`) ) ENGINE = MyISAM DEFAULT CHARSET = utf8 COMMENT = '测试数据库字符集' ; mysql > show tables ; +----------------+ | Tables_in_test | +----------------+ | test_user | +----------------+ 1 rows in set (0.00 sec) |
插入两条测试数据
INSERT INTO `test`.`test_user` (`id`, `username`, `email`) VALUES ('1', '乔布斯', 'jobs@apple.com');
INSERT INTO `test`.`test_user` (`id`, `username`, `email`) VALUES ('2', '苹果', 'apple@apple.com');
INSERT INTO `test`.`test_user` (`id`, `username`, `email`) VALUES ( '1' , '乔布斯' ,'jobs@apple.com' ); INSERT INTO `test`.`test_user` (`id`, `username`, `email`) VALUES ( '2' , '苹果' ,'apple@apple.com' ); |
查询显示乱码，但在我们的网页中不影响使用(因为此表中的数据字符集为utf8，)
mysql> select * from test_user;
+----+----------+-----------------+
| id | username | email |
+----+----------+-----------------+
| 1 | ??? | jobs@apple.com |
| 2 | ?? | apple@apple.com |
+----+----------+-----------------+
2 rows in set (0.00 sec)
mysql > select * from test_user; +----+----------+-----------------+ | id | username | email | +----+----------+-----------------+ | 1 | ??? | jobs@apple.com | | 2 | ?? | apple@apple.com | +----+----------+-----------------+ 2 rows in set (0.00 sec) |
我们做查询时用set names utf8命令
mysql> set names utf8;
Query OK, 0 rows affected (0.00 sec)
mysql > set names utf8; Query OK, 0 rows affected (0.00 sec) |
结果显示正常
mysql> select * from test_user;
+----+-----------+-----------------+
| id | username | email |
+----+-----------+-----------------+
| 1 | 乔布斯 | jobs@apple.com |
| 2 | 苹果 | apple@apple.com |
+----+-----------+-----------------+
2 rows in set (0.00 sec)
mysql > select * from test_user; +----+-----------+-----------------+ | id | username | email | +----+-----------+-----------------+ | 1 | 乔布斯 | jobs@apple.com | | 2 | 苹果 | apple@apple.com | +----+-----------+-----------------+ 2 rows in set (0.00 sec) |
查看此时字符集情况
mysql> show variables like "%char%";
+--------------------------+----------------------------+
| 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 | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)
mysql> show variables like 'collation_%';
+----------------------+-------------------+
| Variable_name | Value |
+----------------------+-------------------+
| collation_connection | utf8_general_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
+----------------------+-------------------+
3 rows in set (0.00 sec)
mysql > show variables like "%char%" ; +--------------------------+----------------------------+ | 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 | latin1 | | character_set_system | utf8 | | character_sets_dir | /usr / share / mysql / charsets/ | +--------------------------+----------------------------+ 8 rows in set (0.00 sec) mysql > show variables like 'collation_%' ; +----------------------+-------------------+ | Variable_name | Value | +----------------------+-------------------+ | collation_connection | utf8_general_ci | | collation_database | latin1_swedish_ci | | collation_server | latin1_swedish_ci | +----------------------+-------------------+ 3 rows in set (0.00 sec) |
现在可以看到client,connection,rsults这三个字符集都已经是utf8（此时我们已经可以正常使用了），但是为了预防一些不正常的插入数据，建议大家把数据库全部设置成utf8，免去一些排查错的麻烦。
[root@test ~]# vim /etc/my.cnf 改成如下
[client]
default-character-set=utf8
[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]
default-character-set=utf8
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[client] default - character - set = utf8 [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] default - character - set = utf8 [mysqld_safe] log - error=/var / log / mysqld. log pid - file =/var / run / mysqld / mysqld.pid |
主要加了以下数据
[client]
default_character_set=utf8
[mysql]
default_character_set=utf8
[mysqld]
default_character_set=utf8
[client] default_character_set = utf8 [mysql] default_character_set = utf8 [mysqld] default_character_set = utf8 |
重启mysql服务
[root@test ~]# /etc/init.d/mysqld restart
停止 mysqld： [确定]
正在启动 mysqld： [确定]
此时查看字符集的情况
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 | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)
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 | /usr / share / mysql / charsets/ | +--------------------------+----------------------------+ 8 rows in set (0.00 sec) |
查看校对字符集
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 (0.00 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 (0.00 sec) |
此时数据库字符集已经全部统一成utf8
MySQL的字符集支持(Character Set Support)有两个方面：
字符集(Character set)和排序方式(Collation)。
对于字符集的支持细化到四个层次:
服务器(server)，数据库(database)，数据表(table)和连接(connection)。
1.MySQL默认字符集
MySQL对于字符集的指定可以细化到一个数据库，一张表，一列，应该用什么字符集。
但是，传统的程序在创建数据库和数据表时并没有使用那么复杂的配置，它们用的是默认的配置，那么，默认的配置从何而来呢？
(1)编译MySQL 时，指定了一个默认的字符集，这个字符集是 latin1；
(2)安装MySQL 时，可以在配置文件 (my.ini) 中指定一个默认的的字符集，如果没指定，这个值继承自编译时指定的；
(3)启动mysqld 时，可以在命令行参数中指定一个默认的的字符集，如果没指定，这个值继承自配置文件中的配置,此时 character_set_server 被设定为这个默认的字符集；
(4)当创建一个新的数据库时，除非明确指定，这个数据库的字符集被缺省设定为character_set_server；
(5)当选定了一个数据库时，character_set_database 被设定为这个数据库默认的字符集；
(6)在这个数据库里创建一张表时，表默认的字符集被设定为 character_set_database，也就是这个数据库默认的字符集；
(7)当在表内设置一栏时，除非明确指定，否则此栏缺省的字符集就是表默认的字符集；
简单的总结一下，如果什么地方都不修改，那么所有的数据库的所有表的所有栏位的都用
latin1 存储，不过我们如果安装 MySQL，一般都会选择多语言支持，也就是说，安装程序会自动在配置文件中把
default_character_set 设置为 UTF-8，这保证了缺省情况下，所有的数据库的所有表的所有栏位的都用 UTF-8 存储。