1、库和表的环境如下，字符集都是latin1：
mysql> show create database yuanqk; +----------+-------------------------------------------------------------------+ | Database | Create Database | +----------+-------------------------------------------------------------------+ | yuanqk | CREATE DATABASE `yuanqk` /*!40100 DEFAULT CHARACTER SET latin1 */ | +----------+-------------------------------------------------------------------+ 1 row in set (0.00 sec) mysql> mysql> use yuanqk Database changed mysql> show create table student; +---------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Table | Create Table | +---------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | student | CREATE TABLE `student` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` char(20) NOT NULL, PRIMARY KEY (`id`), KEY `ind_name` (`name`), KEY `ind_name_age` (`name`) ) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=latin1 | +---------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.00 sec) mysql>
2、插入中文内容后，进行查询，发现是乱码：
mysql> insert into student values(1,'袁清坤'); Query OK, 1 row affected, 1 warning (0.00 sec) mysql> select * from student; +----+------+ | id | name | +----+------+ | 1 | ??? | +----+------+ 1 row in set (0.00 sec)
3、乱码产生的原因，一般是数据库服务端字符集和客户端字符集不一致，查看mysql的字符集
mysql> show variables like 'character_set%'
-> ;
+--------------------------+----------------------------+
| Variable_name | Value |
+--------------------------+----------------------------+
| character_set_client | utf8 | <===客户端字符集为utf8
| character_set_connection | utf8 |
| character_set_database | latin1 | <===数据库字符集为latin1
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /u01/mysql/share/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)
mysql>
4、数据库的字符集这应该是create database的时候设置的，即便修改成了utf8，里面已经插入的数据也必须重新导入也能解决乱码问题，但是使用set names latin1来指定客户端字符集就没问题：
mysql> set names latin1; Query OK, 0 rows affected (0.00 sec) mysql> insert into student values(1,'袁清坤'); ERROR 1062 (23000): Duplicate entry '1' for key 'PRIMARY' mysql> insert into student values(2,'袁清坤'); Query OK, 1 row affected (0.00 sec) mysql> select * from student; +----+-----------+ | id | name | +----+-----------+ | 1 | ??? | | 2 | 袁清坤 | <==中文正常显示了 +----+-----------+ 2 rows in set (0.00 sec) mysql>
5、其实还可以通过登录时指定字符集也是可以的，如：mysql -uroot -pyuanqk yuanqk --default-character-set=latin1 -S /data/3306/mysql.sock 效果是一样的。
6、那set names latin1是对数据库做了什么使得可以正常显示了呢，再看下现在的字符集，客户端和服务器端的字符集一致了。
mysql> show variables like 'character_set%'; +--------------------------+----------------------------+ | Variable_name | Value | +--------------------------+----------------------------+ | character_set_client | latin1 | <===客户端字符集变成latin1了 | character_set_connection | latin1 | <===连接字符集也变成了latin1 | character_set_database | latin1 | | character_set_filesystem | binary | | character_set_results | latin1 | <===这应该是结果返回字符集，也变成latin1了 | character_set_server | latin1 | | character_set_system | utf8 | | character_sets_dir | /u01/mysql/share/charsets/ | +--------------------------+----------------------------+ 8 rows in set (0.00 sec) mysql>
7、那客户端的字符集为什么会是utf8呢？其实如果这些字符集都在my.cnf中进行了设置，那就不会有这种情况，出现这种情况，我觉得一般都是参数文件中没有设置，那这些客户端的字符集就和操作系统的字符集有关，做个测试看看：
[root@mysql 3306]# cat /etc/sysconfig/i18n LANG="en_US.UTF-8" <===这里可以看到操作系统的字符集就是utf8 SYSFONT="latarcyrheb-sun16" [root@mysql 3306]#
--给他换个gb2312看看
[root@mysql 3306]# cat /etc/sysconfig/i18n
#LANG="en_US.UTF-8"
LANG="zh_CN.GB2312" <===换成gb2312
SYSFONT="latarcyrheb-sun16"
[root@mysql 3306]#
[root@mysql 3306]# . /etc/sysconfig/i18n <===使他生效 [root@mysql 3306]# mysql -uroot -pyuanqk -S /data/3306/mysql.sock <===重新连接 Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 4 Server version: 5.5.60-log MySQL Community Server (GPL) Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> show variables like 'character_set%'; <===再次查看数据库字符集 +--------------------------+----------------------------+ | Variable_name | Value | +--------------------------+----------------------------+ | character_set_client | gb2312 | <===客户端相关的字符集全部变成了gb2312了 | character_set_connection | gb2312 | | character_set_database | latin1 | | character_set_filesystem | binary | | character_set_results | gb2312 | | character_set_server | utf8 | | character_set_system | utf8 | | character_sets_dir | /u01/mysql/share/charsets/ | +--------------------------+----------------------------+ 8 rows in set (0.00 sec) mysql> mysql> select * from student; <===再查询，显示的全是乱码 +----+--------------+ | id | name | +----+--------------+ | 1 | ??? | | 2 | ��????��??�� | | 5 | ?????�� | | 6 | ?????? | +----+--------------+ 4 rows in set (0.05 sec) mysql>
9、然后再设置set names llatin1就又可以显示中文了，因此乱码一般就是客户端和服务器端的字符集不一致导致的，对于客户端的字符集又和操作系统的字符集有关系。最好的办法就是全部写在配置文件中。
mysql> set names latin1
-> ;
Query OK, 0 rows affected (0.00 sec)
mysql> select * from student;
+----+-----------+
| id | name |
+----+-----------+
| 1 | ??? |
| 2 | 袁清坤 |
| 5 | 张三 |
| 6 | 李四 |
+----+-----------+
4 rows in set (0.00 sec)
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 | utf8 |
| character_set_system | utf8 |
| character_sets_dir | /u01/mysql/share/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)
mysql>