MySQL字符乱码解决方案

1、字符集对应查看

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 |
| 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 |
+----------+-----------------------------+---------------------+--------+
39 rows in set (0.00 sec)

2.查看字符集变量

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       | /app55/mysql-5.5.45/share/charsets/ |
+--------------------------+-------------------------------------+
8 rows in set (0.00 sec)

3.乱码原因

客户端字符集
character_set_client
character_set_connection
character_set_results
数据库字符集：
Character_set_server
character_set_database
character_set_system
这两种字符集不相同导致。

4.解决字符集乱码
1).已经有数据库，但是插入数据时乱码，需要如下

mysql> show  create  database  virtual;
+----------+------------------------------------------------------------------+
| Database | Create Database                                                  |
+----------+------------------------------------------------------------------+
| virtual  | CREATE DATABASE `virtual` /*!40100 DEFAULT CHARACTER SET utf8 */ |
+----------+------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> use  virtual;
Database changed
mysql> show  create  table user;
+-------+-----------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                          |
+-------+-----------------------------------------------------------------------------------------------------------------------+
| user  | CREATE TABLE `user` (
`id` int(11) NOT NULL,
`name` varchar(20) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+-----------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

操作前，先set names库和表的character。

2).没有数据库，那么在建立数据库的时候指定数据库格式。

mysql> create database test default character set gbk collate gbk_chinese_ci;
mysql> create   table  user  (id  int not null,name  varchar(20));
mysql> show  create table  user;
+-------+----------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                         |
+-------+----------------------------------------------------------------------------------------------------------------------+
| user  | CREATE TABLE `user` (
`id` int(11) NOT NULL,
`name` varchar(20) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=gbk |

默认继承数据库的字符集
+-------+----------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
然后，
set  names  ‘gbk’,
再次操作。

3).直接导入sql文件，怎么解决乱码

3.1 sql文件中，加上set names utf8
3.2 mysql>set names utf8;
mysql>source file.sql
3.3 mysql命令使用--default-character-set=utf8 导入sql文件
Mysql –uadmin –p’jidian123’ –S /mydata/mysql.sock –default-character-set=utf8

5.set names ‘utf8’ 和—default-character-set=utf8具体干了些什么？

它们都干了相同的事，把下面3个变量的值变成和要操作的数据库字符集相同了。
character_set_client     | utf8                                | character_set_connection | utf8

|
| character_set_results    | utf8

|

6、结论
字符集乱码问题受4个东西影响。
1）客户端字符集,3个字符集受Linux系统字符集影响。

character_set_client
character_set_connection
character_set_results

2）要操作的数据库的字符集

Show  create  database test;

3）要操作的数据表的字符集

Use  test;
Show  create  table  user

7．更改配置文件
客户端字符集,编辑my.cnf

vi /etc/my.cnf
[client]
default-character-set = utf8     <===set names 'utf8'
注意：客户端修改字符集不需要重启服务器

服务端字符集，编辑my.cnf

vi /etc/my.cnf
[mysqld]
default-character-set = utf8       mysql5.1
character-set-server = utf8        mysql5.5

注意：服务端修改字符集需要重启服务器

8大结论：
1）linux服务器字符集

CentOS6
系列
vi /etc/sysconfig/i18n
LANG="en_CN.UTF-8"
CentOS7
系列
vi  /etc/locale.conf
LANG="en_CN.UTF-8"

2）linux客户端字符集

secureCRT
工具

3）MySQL服务器字符集配置
永久生效
vi /etc/my.cnf

[mysqld]
default-character-set=utf8    mysql5.1
版本
character-set-server=utf8     mysql5.5
版本
重启服务器
提示：
更改后变化的变量
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       | /app55/mysql-5.5.45/share/charsets/

4）MySQL客户端字符集配置
临时生效：

1、set names 'utf8'
2、mysql -uadmin -p -S /mydata/mysql.sock --default-character-set=utf8

提示：
更改后受影响的变量

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       | /app55/mysql-5.5.45/share/charsets/

永久生效

vi /etc/my.cnf
[client]
default-character-set = utf8

提示：
不需要重启服务器，数据证明一切。 并且客户端字符集不会再受linux字符集的影响了。

9.生成环境更改字符集
对已有数据的数据库进行字符集转变，没有没有作用。只能导出数据，重新建库建表。

改库：
alter database character set 'ut8';
改表：
alter table  character set 'utf8';

生产环境更改字符集方法：latin1 utf8
1）导出表结构

mysqldump -uadmin -p'jidian123' -S /mydata/mysql.sock -d virtual >virtual_bak.sql
sed -i 's/latin1/utf8/g'   virtual_bak.sql

2.建库

create  database virtual default character set utf8 collate utf8_general_ci;

3.更改MySQL默认字符集

[client]
default-character-set = utf8
[mysqld]
character-set-server = utf8       mysql5.5
配置
default-character-set = utf8     mysql5.1
配置

重启数据库

4.导入数据

mysql -uadmin -p'jidian123' -S /mydata/mysql.sock  virtual < virtual_bak.sql