本文目录 [隐藏]
I. MySQL5.5字符集介绍
II. 什么是字符集？
字符集，character set，就是一套表示字符的符号和这些的符号的底层编码；而校验规则，则是在字符集内用于比较字符的一套规则。
简单的说，字符集就是一套文字符号及其编码、比较规则的集合，第一个计算机字符集ASC2，MySQL数据库字符集包括字符集和校对规则两个概念，字符集是定义数据库里面的内容字符串的存储方式，而校对规则是定义比较字符串的方式
编译MySQL的时候，指定字符集了，这样以后建库的时候就直接create database db_name;
二进制安装MySQL，就没有指定字符集了，此时字符集默认就是latinl，此时需要建立UTF8字符集的库，就要指定UTF8字符集建库
create database oldboy default character set utf8 deaultcollate=utf8_general_ci;在互联网环境中，使用MySQL时常用的字符集
| 常用字符集 | 一个汉字长度（字节） | 说明 |
|---|---|---|
| GBK | 2 | 不是国际标准，对中文支持的很好 |
| UTF-8 | 3 | 中英文混合的环境，建议使用此字符集，用的比较多的 |
| Latinl | 1 | MySQL的默认字符集 |
| Utf8mb4 | 4 | UTF-8 Unicode,移动互联网 |
工作中MySQL如何选择字符集？
- 如果处理各种各样的文字，发布到不同语言国家地区，应选Unicode字符集。对mysql来说就是UTF-8（每个汉字三字节），如果应用需处理英文，仅有少量汉字UTF-8更好。
- 如只需支持中文，并且数据量很大，性能要求也很高，可以选择GBK（定长 每个汉字占双字节，英文也占双字节），如果需大量运算，比较排序等，定义长字符集，更快，性能高
- 处理移动互联网业务，可能需要使用utf8mb4字符集
III. MySQL字符集相关命令
查看MySQL字符集设置情况
mysql> show variables like 'character%';
[root@MySQL ~]# mysql -uroot -p3306 -S /data/3306/mysql.sock -e "show variables like 'character%'"
+--------------------------+----------------------------+
| Variable_name | Value |
+--------------------------+----------------------------+
| character_set_client | utf8 | --客户端字符集
| character_set_connection | utf8 | --连接字符集，客户端
| character_set_database | utf8 | --数据库字符集，配置文件指定或建库表指定
| character_set_filesystem | binary | --文件系统的字符集
| character_set_results | utf8 | --返回结果字符集 客户端
| character_set_server | utf8 | --服务器字符集，配置文件指定或建库表指定
| character_set_system | utf8 | --系统的字符集查看字符集及校验规则
[root@MySQL ~]# mysql -uroot -p3306 -S /data/3306/mysql.sock -e "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 |
| 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 |
| 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 |
| 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 |
| 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 |
+----------+-----------------------------+---------------------+--------+查看库的字符集
mysql> show create database db;
+----------+-------------------------------------------------------------+
| Database | Create Database |
+----------+-------------------------------------------------------------+
| db | CREATE DATABASE `db` /*!40100 DEFAULT CHARACTER SET utf8 */ |
+----------+-------------------------------------------------------------+查看表的字符集
mysql> show create table db_tb\G
*************************** 1. row ***************************
Table: db_tb
Create Table: CREATE TABLE `db_tb` (
`id` int(4) DEFAULT NULL,
`name` varchar(16) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8查询MySQL数据库所支持的字符集和校验规则
- 查询所有
mysql> show collation;- like进行筛选，之查看utf8的
mysql> show collation like 'utf8%';
+--------------------------+---------+-----+---------+----------+---------+
| Collation | Charset | Id | Default | Compiled | Sortlen |
+--------------------------+---------+-----+---------+----------+---------+
| utf8_general_ci | utf8 | 33 | Yes | Yes | 1 |
| utf8_bin | utf8 | 83 | | Yes | 1 |
| utf8_unicode_ci | utf8 | 192 | | Yes | 8 |
| utf8_icelandic_ci | utf8 | 193 | | Yes | 8 |
| utf8_latvian_ci | utf8 | 194 | | Yes | 8 |
| utf8_romanian_ci | utf8 | 195 | | Yes | 8 |
| utf8_slovenian_ci | utf8 | 196 | | Yes | 8 |
| utf8_polish_ci | utf8 | 197 | | Yes | 8 |
| utf8_estonian_ci | utf8 | 198 | | Yes | 8 |
| utf8_spanish_ci | utf8 | 199 | | Yes | 8 |
| utf8_swedish_ci | utf8 | 200 | | Yes | 8 |
| utf8_turkish_ci | utf8 | 201 | | Yes | 8 |
| utf8_czech_ci | utf8 | 202 | | Yes | 8 |
| utf8_danish_ci | utf8 | 203 | | Yes | 8 |
| utf8_lithuanian_ci | utf8 | 204 | | Yes | 8 |
| utf8_slovak_ci | utf8 | 205 | | Yes | 8 |
| utf8_spanish2_ci | utf8 | 206 | | Yes | 8 |
| utf8_roman_ci | utf8 | 207 | | Yes | 8 |
| utf8_persian_ci | utf8 | 208 | | Yes | 8 |
| utf8_esperanto_ci | utf8 | 209 | | Yes | 8 |
| utf8_hungarian_ci | utf8 | 210 | | Yes | 8 |
| utf8_sinhala_ci | utf8 | 211 | | Yes | 8 |
| utf8_general_mysql500_ci | utf8 | 223 | | Yes | 1 |
| utf8mb4_general_ci | utf8mb4 | 45 | Yes | Yes | 1 |
| utf8mb4_bin | utf8mb4 | 46 | | Yes | 1 |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 8 |
| utf8mb4_icelandic_ci | utf8mb4 | 225 | | Yes | 8 |
| utf8mb4_latvian_ci | utf8mb4 | 226 | | Yes | 8 |
| utf8mb4_romanian_ci | utf8mb4 | 227 | | Yes | 8 |
| utf8mb4_slovenian_ci | utf8mb4 | 228 | | Yes | 8 |
| utf8mb4_polish_ci | utf8mb4 | 229 | | Yes | 8 |
| utf8mb4_estonian_ci | utf8mb4 | 230 | | Yes | 8 |
| utf8mb4_spanish_ci | utf8mb4 | 231 | | Yes | 8 |
| utf8mb4_swedish_ci | utf8mb4 | 232 | | Yes | 8 |
| utf8mb4_turkish_ci | utf8mb4 | 233 | | Yes | 8 |
| utf8mb4_czech_ci | utf8mb4 | 234 | | Yes | 8 |
| utf8mb4_danish_ci | utf8mb4 | 235 | | Yes | 8 |
| utf8mb4_lithuanian_ci | utf8mb4 | 236 | | Yes | 8 |
| utf8mb4_slovak_ci | utf8mb4 | 237 | | Yes | 8 |
| utf8mb4_spanish2_ci | utf8mb4 | 238 | | Yes | 8 |
| utf8mb4_roman_ci | utf8mb4 | 239 | | Yes | 8 |
| utf8mb4_persian_ci | utf8mb4 | 240 | | Yes | 8 |
| utf8mb4_esperanto_ci | utf8mb4 | 241 | | Yes | 8 |
| utf8mb4_hungarian_ci | utf8mb4 | 242 | | Yes | 8 |
| utf8mb4_sinhala_ci | utf8mb4 | 243 | | Yes | 8 |
+--------------------------+---------+-----+---------+----------+---------+IV. 调整字符集方式
调整当前客户端字符集
语法格式
set names [character set]
在登录时调整字符集
语法格式
mysql -u[user] -p[password] --default-character-set=[character set]
实战演练set names更改字符集方式
- 创建一个数据库为名称为db
mysql> create database db;
Query OK, 1 row affected (0.00 sec)- 查看db库字符集
mysql> show create database db;
+----------+-------------------------------------------------------------+
| Database | Create Database |
+----------+-------------------------------------------------------------+
| db | CREATE DATABASE `db` /*!40100 DEFAULT CHARACTER SET utf8 */ |
+----------+-------------------------------------------------------------+
1 row in set (0.00 sec)- 进入库db，创建一个表名称为db_table
mysql> use db
Database changed
mysql> create table db_table(id int(4),name char(10));
Query OK, 0 rows affected (0.01 sec)- 查看表db_table的字符集
mysql> show create table db_table\G
*************************** 1. row ***************************
Table: db_table
Create Table: CREATE TABLE `db_table` (
`id` int(4) DEFAULT NULL,
`name` char(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)- 往字段id和name插入内容
mysql> insert into db_table(id,name) values(1,'张三');
Query OK, 1 row affected (0.00 sec)- 查看刚插入的内容，现在我们发现并没有乱码
mysql> select * from db_table;
+------+--------+
| id | name |
+------+--------+
| 1 | 张三 |
+------+--------+
1 row in set (0.00 sec)- 修改当前的字符集为gbk
mysql> set names gbk;
Query OK, 0 rows affected (0.00 sec)- 查看当前数据库的字符集设置情况，我们发现客户端的三个选项都变成了GBK的字符集
mysql> show variables like 'character_set%';
+--------------------------+-------------------------------------------+
| Variable_name | Value |
+--------------------------+-------------------------------------------+
| character_set_client | gbk |
| character_set_connection | gbk |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | gbk |
| character_set_server | utf8 |
| character_set_system | utf8 |
| character_sets_dir | /application/mysql-5.5.32/share/charsets/ |
+--------------------------+-------------------------------------------+
8 rows in set (0.00 sec)- 往字段内插入内容
mysql> insert into db_table(id,name) values(2,'李四');
Query OK, 1 row affected (0.04 sec)- 查看表内容，这是我们就发现乱码了
mysql> select * from db_table;
+------+--------+
| id | name |
+------+--------+
| 1 | օɽ |
| 2 | 李四 |
+------+--------+
2 rows in set (0.03 sec)- 再把字符集改为utf8
mysql> set names utf8;
Query OK, 0 rows affected (0.00 sec)- 查看当前数据库的字符集设置情况
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 | /application/mysql-5.5.32/share/charsets/ |
+--------------------------+-------------------------------------------+
8 rows in set (0.00 sec)- 再查看表内容，我们发现刚才修改字符集为gbk时插入的内容已经乱码了
mysql> select * from db_table;
+------+-----------+
| id | name |
+------+-----------+
| 1 | 张三 |
| 2 | 鏉庡洓 |
+------+-----------+
2 rows in set (0.00 sec)小结：字符集不同我们创建或者查看的内容都会变成乱码，而set names只是修改当前的字符集情况
执行SQL文件插入中文数据不乱码方法
- 在执行SQL语句之前更改字符集
[root@MySQL ~]# cat db.sql
SET NAMES UTF8；
CREATE DATABASE /*!32312 IF NOT EXISTS*/ `db` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `db`;
DROP TABLE IF EXISTS `db_table`;
CREATE TABLE `db_table` (
`id` int(4) DEFAULT NULL,
`name` char(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
LOCK TABLES `db_table` WRITE;
INSERT INTO `db_table` VALUES (1,'张三'),(2,'鏉庡洓');
UNLOCK TABLES;- SQL语句导入的时候指定字符集
[root@MySQL ~]# mysql -uroot -p123456 --default-character-set=utf8 oldboy < db.sql永久更改字符集
通过修改更my.cnf实现修改mysql客户端的字符集
- 客户端
[client]
character-set-server=utf8- 服务端
[mysqld]
character-set-server=utf8 --适合5.5
default-characyer-set=utf8 --适合5.1命令方式永久更改字符集
- 修改数据库库默认编码
help alter database
alter database [your db name] charset [your character settting]
mysql> show character set;下面方法只能适应新数据，老数据字符集没有更改，库内的表也没有改
mysql> alter database oldboy CHARACTER SET latin1 COLLATE = latin1_swedish_ci;
mysql> show create database oldboy\g更改表
mysql> show create table test\G统一MySQL数据库客户及服务端字符集总结
- 客户端字符集设置为“set names utf8”，这样可以确保插入后的中文，不出现乱码，但是对执行set names utf8;前插入的中文无效，此命令临时生效
- 和设置客户端字符集“set names utf8”命令有相同作用的方法还有，mysql命令指定utf8字符集参数登录，以及在my.cnf里更改参数实现。
- 在MySQL的my.cnf配置文件里的[client]模块下添加字符集配置，生效后，相当于命令行“set names utf8；”的效果，由于更改的是客户端、连接和返回结果三个字符集，应此无需重启服务就生效。
- 在MySQL的my.cnf配置文嘉你的[mysqld]模块下添加字符集配置，生效后，创建数据库和表默认都是这个设置的字符集，MySQL5.5和5.1的服务端字符集参数有变化，具体为character-set-server=utf8参数适合5.5，default-character-set=utf8参数适合5.1及以前版本。
- 不乱码的思想就是Linux服务器和MySQL数据库，以及创建的库和表的字符集都保持一致，还有客户端CRT或者Xshell的字符集也要保持一致。
更改字符集总的思想
- 数据库不要更新，到处所有数据。
- 把导出的数据进行字符集替换。
- 修改my.cnf，更改MySQL客户端服务端字符集，重启生效。
- 到处更改过字符集的数据包括表结构语句，提供服务。
V. 如何调整已有MySQL数据库的字符集，例如：从UTF8改成GBK
- 查看当前系统的字符集设置
mysql> show variables like 'character%';
+--------------------------+-------------------------------------------+
| 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 | /application/mysql-5.5.32/share/charsets/ |
+--------------------------+-------------------------------------------+
#可以看到客户端服务端和服务器的字符集都是utf8- 查看db库和表的字符集,这里就以一个数据库为例子，如果有很多数据库和表可以用脚本实现
mysql> mysql -uroot -p3306 -S /data/3306/mysql.sock -e "show create database db;
+----------+-------------------------------------------------------------+
| Database | Create Database |
+----------+-------------------------------------------------------------+
| db | CREATE DATABASE `db` /*!40100 DEFAULT CHARACTER SET utf8 */ | --表的字符集为utf8
+----------+-------------------------------------------------------------+
mysql> show create table db.test\G
*************************** 1. row ***************************
Table: test
Create Table: CREATE TABLE `test` (
`id` int(4) DEFAULT NULL,
`name` char(16) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 --库的字符集为utf8
1 row in set (0.00 sec)- 查看表的内容
mysql> select * from db.test;
+------+--------+
| id | name |
+------+--------+
| 1 | sa |
| 2 | 测试 | ---中文并没有乱码
+------+--------+
2 rows in set (0.00 sec)- 把数据库db以SQL语句的形式导出
[root@MySQL ~]# mysqldump -uroot -p3306 -S /data/3306/mysql.sock -B db>db.sql
[root@MySQL ~]# egrep -v "^-|^\/|^$" db.sql
CREATE DATABASE /*!32312 IF NOT EXISTS*/ `db` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `db`;
DROP TABLE IF EXISTS `test`;
CREATE TABLE `test` (
`id` int(4) DEFAULT NULL,
`name` char(16) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
LOCK TABLES `test` WRITE;
INSERT INTO `test` VALUES (1,'sa'),(2,'测试');
UNLOCK TABLES;
#现在可以看到有很多utf8的字符，这是都是自创建表的时候指定的字符集- 修改备份文件的SQL语句utf8改为gbk
[root@MySQL ~]# cp db.sql db_bak.sql #先做备份
[root@MySQL ~]# sed -i 's#utf8#gbk#g' db.sql #把utf8全部改成gbk
[root@MySQL ~]# egrep -v "^-|^\/|^$" db.sql
CREATE DATABASE /*!32312 IF NOT EXISTS*/ `db` /*!40100 DEFAULT CHARACTER SET gbk */;
USE `db`;
DROP TABLE IF EXISTS `test`;
CREATE TABLE `test` (
`id` int(4) DEFAULT NULL,
`name` char(16) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=gbk;
LOCK TABLES `test` WRITE;
INSERT INTO `test` VALUES (1,'sa'),(2,'测试');
UNLOCK TABLES;
#可以看到现在的SQL语句字符集是GBK- 修改配置文件my.cnf指定客户端和服务端字符集为gbk
[root@MySQL ~]# vim /data/3306/my.cnf
[client]
character-set-server=gbk
[mysqld]
character-set-server=gbk
#在客户端和服务端模块中指定字符集为gbk- 更改系统的字符集为GBK
[root@MySQL ~]# vim /etc/sysconfig/i18n
#LANG="en_US.UTF-8"
LANG="zh_CN.GBK"
#LANG="zh_CN.UTF-8"
SYSFONT="latarcyrheb-sun16"
[root@MySQL ~]# reboot
#原有的字符集注销掉不删除，以免出错- 修改客户端Xshell字符集为gbk
- 删除数据库中的所有数据
mysql> drop database db;
Query OK, 1 row affected (0.07 sec)
mysql> show databases;
+######--+
| Database |
+######--+
| information_schema |
| mysql |
| performance_schema |
+######--+
3 rows in set (0.03 sec)
#这里只是测试，所以就只删除了db库- 导入mysql的所有数据
[root@MySQL ~]# mysql -uroot -p3306 -S /data/3306/mysql.sock < db.sql- 查看字符集及数据
mysql> show variables like 'character%';
+########--+##############-+
| Variable_name | Value |
+########--+##############-+
| character_set_client | gbk |
| character_set_connection | gbk |
| character_set_database | gbk |
| character_set_filesystem | binary |
| character_set_results | gbk |
| character_set_server | gbk |
| character_set_system | gbk |
| character_sets_dir | /application/mysql-5.5.32/share/charsets/ |
+########--+##############-+
8 rows in set (0.00 sec)
#现在系统的字符集都变成了gbk了
mysql> show create database db;
+###-+####################+
| Database | Create Database |
+###-+####################+
| db | CREATE DATABASE `db` /*!40100 DEFAULT CHARACTER SET gbk */ |
+###-+####################+
1 row in set (0.00 sec)
#db库的字符集现在也是gbk了
mysql> show create table db.test\G
*************************** 1. row ***************************
Table: test
Create Table: CREATE TABLE `test` (
`id` int(4) DEFAULT NULL,
`name` char(16) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=gbk
1 row in set (0.00 sec)
#表的字符集也是gbk
mysql> show databases;
+######--+
| Database |
+######--+
| information_schema |
| db |
| mysql |
| performance_schema |
+######--+
4 rows in set (0.00 sec)
#查看有数据库db
mysql> use db
Database changed
mysql> show tables;
+####--+
| Tables_in_db |
+####--+
| test |
+####--+
1 row in set (0.00 sec)
#test表也存在
mysql> select * from db.test;
+##+##--+
| id | name |
+##+##--+
| 1 | sa |
| 2 | 测试 |
+##+##--+
2 rows in set (0.00 sec)
#查看表内容中文也没有乱码总结：utf8 >> gbk