乱码问题的罪魁祸首是字符问题
字符集：
简单来说，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(character)和校对规则(collation),两个概念，其中，字符集用了定义mysql数据字符串的存储方式，而校对规则是定义比较字符集的方式。
在上面的命令查看已建立lvnian库语句中，character set latin1 即为数据字符集，而collation latin1_sedish_ci为校对规则。
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查看字符集和校对规则的命令： show character set;
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 |
| cp1251 | Windows Cyrillic | cp1251_general_ci | 1 |
| cp1256 | Windows Arabic | cp1256_general_ci | 1 |
| cp1257 | Windows Baltic | cp1257_general_ci | 1 |
| 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 |
+----------+-----------------------------+---------------------+--------+
36 rows in set (0.00 sec)
mysql>
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查看当前mysql字符集
mysql> show variables like 'character_set%' ;
+--------------------------+------------------------------------------------+
| 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 | /application/mysql5.1.72/share/mysql/charsets/ |
+--------------------------+------------------------------------------------+
8 rows in set (0.00 sec)
客户端字符集（character_set_client）、连接字符集(character_set_connection)、返回结果字符集(character_set_results)，在没有设定特定的字符集的情况下，和linux（/etc/sysconfig/i18n）字符集有关。
指定这三种字符集方法
方法1.临时生效
mysql 进入数据库，再执行set names xxx（字符集如latin1）;
方法2.临时生效
mysql -uroot -p"lvnian" --default-character-set=latin1 lvnian
方法3.永久生效
修改my.cnf配置文件。
[client]
default-character-set=latin1
#####################################
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方法1；
登录mysql，先做set names latin1;
前提是你的创建的表是（ENGINE=MyISAM DEFAULT CHARSET=latin1）latin1字符集。
如果你的表是gbk，那就set names gbk;
这种方法是临时的，也就是你每次登录的时候都要set names latin1
下面的1其他几种方法也要遵守这个前提。
查看表是哪一种字符集的方法
mysql> show create table lvnian\G;
*************************** 1. row ***************************
Table: lvnian
Create Table: CREATE TABLE `lvnian` (
`id` int(4) NOT NULL,
`name` char(20) NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
1 row in set (0.00 sec)
ERROR:
No query specified
方法2
在sql 文件中set names latin1；然后登录mysql，通过执行下面命令
cat > test.sql<<EOF
set name latin1;
insert into lvnian values(4,'小王');
EOF
登录mysql ，执行下面命令
source test.sql
方法3
在sql 文件中set names latin1；然后登录mysql，通过执行下面命令
cat > test.sql<<EOF
set name latin1;
insert into lvnian values(4,'小王');
EOF
登录mysql ，执行下面命令
mysql -uroot -p"lvnian" lvnian < test.sql
mysql -uroot -p"lvnian" -e"set name latin1;select * from lvnian.lvnian"
方法4
通过指定mysql命令字符集参数实现 --default-character-set=latin1
cat > test.sql<<EOF
insert into lvnian values(4,'小王');
EOF
====
mysql -uroot -p"lvnian" --default-character-set=latin1 lvnian < test.sql
mysql -uroot -p"lvnian" -e"set name latin1;select * from lvnian.lvnian"
方法5
在配置文件中设置客户端和服务端的相关参数
更改my.cnf客户端模块的参数，可以实现set names latin1 的效果并且永久生效
[client]
default-character-set=latin1
提升：修改客户端的配置文件无需重启服务，保存推迟重新登录mysql就生效，相当于set names latin1
更改服务端
[mysqld]
default-character-set=latin1 ##适合5.1 版本
character-set-server=latin1 ##适合5.5 版本
###########################################################################
保证不乱码思想：
mysql客户端、mysql服务端、库、表、程序、系统字符集都设置一致就不乱码了
linux 系统字符集修改地方
[root@MySQL ~]# cat /etc/sysconfig/i18n
LANG="en_US.UTF-8"
SYSFONT="latarcyrheb-sun16"
[root@MySQL ~]#
客户端字符集
临时生效
set names utf8 ##这个就是在修改客户端字符集
或者
下面是永久生效
[client]
default-character-set=utf8
服务端字符集
[mysqld]
default-character-set=utf8 ##适合5.1 版本
character-set-server=utf8 ##适合5.5 版本
库表
create database lvnian default character set utf8
CREATE TABLE `lvnian1` (
`id` int(4) NOT NULL,
`name` char(20) NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
查看字符类型的校对规则
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 |
| cp1251 | Windows Cyrillic | cp1251_general_ci | 1 |
| cp1256 | Windows Arabic | cp1256_general_ci | 1 |
| cp1257 | Windows Baltic | cp1257_general_ci | 1 |
| 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 |
+----------+-----------------------------+---------------------+--------+
36 rows in set (0.00 sec)
mysql>
