实战

1、安装MySQL数据库

2、乱码演示

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/local/mysql/share/charsets/ |+--------------------------+----------------------------------+8 rows in set (0.00 sec) mysql> insert into test.table10 values (1,'云中鹤');Query OK, 1 row affected (0.00 sec) mysql> select * from test.table10;+------+-----------+| id   | names     |+------+-----------+|    1 | 云中鹤    |+------+-----------+1 row in set (0.00 sec) mysql> set names latin1;Query OK, 0 rows affected (0.00 sec) mysql> select * from test.table10;+------+-------+| id   | names |+------+-------+|    1 | ???   |+------+-------+1 row in set (0.00 sec) mysql> show variables like 'character_set%';+--------------------------+----------------------------------+| Variable_name            | Value                            |+--------------------------+----------------------------------+| character_set_client     | latin1    #客户端来源数据使用的字符集                       | character_set_connection | latin1    # 连接层字符集| character_set_database   | utf8       #当前选中数据库的默认字符集                        | character_set_filesystem | binary                  | character_set_results    | latin1    #查询结果字符集   || character_set_server     | utf8       #默认的内部操作字符集                      || character_set_system     | utf8      #系统元数据(字段名等)字符集                                 | character_sets_dir       | /usr/local/mysql/share/charsets/ |+--------------------------+----------------------------------+8 rows in set (0.00 sec)

乱码解决办法

从上面可以看出，set names latin1;改变了三个参数.. 只要做到客户端，MySQL character-set-client，table charset三个字符集完全一致就可以保证一定不会有乱码出现。

方式:

1、在mysql命令行模式下执行set names xxx;

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

2、登录mysql的时候指定默认字符集

       [root@node1 ~]# mysql -S /tmp/mysql.sock4 --defaults-character-set=utf8  #-S 指定多实例mysql的套接字文件，       使用--defaults-character-set 指定默认字符集。

3、修改/etc/sysconfig/i18n 文件，在my.cnf不指定默认字符集的情况下。

       vim /etc/sysconfig/i18n       LANG='zh_CN.UTF-8'   #如果my.cnf不指定，默认使用系统字符集

4、修改my.cnf 文件，下面两个字段在任意一个字段都是可以的。

       [client]       default-character-set=latin1

       [mysql]       default-character-set=latin1

前两种1,2是临时解决方案，后面两种3,4是永久有效的方案

查看字符集

1、查看系统当前字符集设置，修改之后登陆mysql执行。show variables lile 'character_set%';

mysql> show variables like 'character_set%';#我修改的为utf8，所以客户端的三个参数都是utf8.你可以自行设置字符集。+--------------------------+----------------------------------+| 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/share/charsets/ |

2、mysql常用字符集。执行命令show character set; 查看系统支持字符集。

mysql> show character set;+----------+-----------------------------+---------------------+--------+| Charset  | Description                 | Default collation   | Maxlen |+----------+-----------------------------+---------------------+--------+| big5     | Big5 Traditional Chinese    | big5_chinese_ci     |      2 || dec8     | DEC West European           | dec8_swedish_ci     |      1 || cp850    | DOS West European           | cp850_general_ci    |      1 || hp8      | HP West European            | hp8_english_ci      |      1 || koi8r    | KOI8-R Relcom Russian       | koi8r_general_ci    |      1 || latin1   | cp1252 West European        | latin1_swedish_ci   |      1 |   #常用| latin2   | ISO 8859-2 Central European | latin2_general_ci   |      1 || swe7     | 7bit Swedish                | swe7_swedish_ci     |      1 || ascii    | US ASCII                    | ascii_general_ci    |      1 || ujis     | EUC-JP Japanese             | ujis_japanese_ci    |      3 || sjis     | Shift-JIS Japanese          | sjis_japanese_ci    |      2 || hebrew   | ISO 8859-8 Hebrew           | hebrew_general_ci   |      1 || tis620   | TIS620 Thai                 | tis620_thai_ci      |      1 || euckr    | EUC-KR Korean               | euckr_korean_ci     |      2 || koi8u    | KOI8-U Ukrainian            | koi8u_general_ci    |      1 || gb2312   | GB2312 Simplified Chinese   | gb2312_chinese_ci   |      2 || greek    | ISO 8859-7 Greek            | greek_general_ci    |      1 || cp1250   | Windows Central European    | cp1250_general_ci   |      1 || gbk      | GBK Simplified Chinese      | gbk_chinese_ci      |      2 | #常用| latin5   | ISO 8859-9 Turkish          | latin5_turkish_ci   |      1 || armscii8 | ARMSCII-8 Armenian          | armscii8_general_ci |      1 || utf8     | UTF-8 Unicode               | utf8_general_ci     |      3 |#常用| ucs2     | UCS-2 Unicode               | ucs2_general_ci     |      2 || cp866    | DOS Russian                 | cp866_general_ci    |      1 || keybcs2  | DOS Kamenicky Czech-Slovak  | keybcs2_general_ci  |      1 || macce    | Mac Central European        | macce_general_ci    |      1 || macroman | Mac West European           | macroman_general_ci |      1 || cp852    | DOS Central European        | cp852_general_ci    |      1 || latin7   | ISO 8859-13 Baltic          | latin7_general_ci   |      1 || utf8mb4  | UTF-8 Unicode               | utf8mb4_general_ci  |      4 | #常用| cp1251   | Windows Cyrillic            | cp1251_general_ci   |      1 || utf16    | UTF-16 Unicode              | utf16_general_ci    |      4 || cp1256   | Windows Arabic              | cp1256_general_ci   |      1 || cp1257   | Windows Baltic              | cp1257_general_ci   |      1 || utf32    | UTF-32 Unicode              | utf32_general_ci    |      4 || binary   | Binary pseudo charset       | binary              |      1 || geostd8  | GEOSTD8 Georgian            | geostd8_general_ci  |      1 || cp932    | SJIS for Windows Japanese   | cp932_japanese_ci   |      2 || eucjpms  | UJIS for Windows Japanese   | eucjpms_japanese_ci |      3 |+----------+-----------------------------+---------------------+--------+39 rows in set (0.00 sec)

字符集选择

1、如果处理各种各样的文字，发布到不同语言国家地区，选择Unicode。，对mysql对号utf-8。

2、只需中文，数据量很大，性能要求也高，选择gbk.。

3、处理移动物联网业务，选utf8mb4

建议在能够完全满足应用的前提下，尽量使用小的字符集。因为更小的字符集意味着能够节省空间、减少网络传输字节数，同时由于存储空间的较小间接的提高了系统的性能。

服务器字符集设置

[mysqld]...character-set-server=utf8   #添加这条语句，可设置服务器端字符集。

mysql服务端重新启动后，这两个参数会改变为设定值。

| character_set_server     | utf8    | character_set_database   | utf8

切换字符集

将一种编码的数据库转换为另一种编码的数据。

alter database dbname character set xxx; #只能对以后的数据有效，对之前的数据无效。基本不使用

常用转换数据库字符集方案

mysqldump -S /tmp/mysql.sock4 --default-character-set=utf8 -d test > /data/test-`date +%F`.sql #1、导出表结构而不导出数据vim /data/test-`date +%F`.sqlDROP TABLE IF EXISTS `table10`;/*!40101 SET @saved_cs_client     = @@character_set_client */;/*!40101 SET character_set_client = utf8 */;CREATE TABLE `table10` (  `id` int(11) DEFAULT NULL,  `names` char(20) DEFAULT NULL) ENGINE=InnoDB DEFAULT CHARSET=utf8;  #2、这里的CHARSET改为你想要修改的字符集mysqldump -S /tmp/mysql.sock4 --extended-insert --no-create-info test > /data/test-data-`date +%F`.sql  #3、导出数据内容vim /data/test-data-`date +%F`.sqlLOCK TABLES `table10` WRITE;set names utf8;  #4、这一行是多加的，自己指定想要转换的字符集INSERT INTO `table10` VALUES (1,'云中鹤');UNLOCK TABLES;mysql> create database if not exists test;  #5、创建数据库，存储转换后的数据Query OK, 1 row affected, 0 warning (0.00 sec)mysql -S /tmp/mysql.sock4 test < /data/test-`date +%F`.sql  #6、导入表结构mysql -S /tmp/mysql.sock4 test < /data/test-data-2015-09-25.sql   #7、导入表数据