1）MySQL插入中文数据乱码问题：
模拟乱码现象：
mysql> create database kitty;
Query OK, 1 row affected (0.00 sec)
mysql> show create database kitty\G;
*************************** 1. row ***************************
Database: kitty
Create Database: CREATE DATABASE `kitty`
1 row in set (0.00 sec)
ERROR:
No query specified
mysql> alter database kitty character set latin1;
Query OK, 1 row affected (0.01 sec)
mysql> flush privileges；
mysql> use kitty;
Database changed
创建teacher表（字符集为latin1）：
CREATE TABLE `teacher` (
`id` int(4) NOT NULL,
`name` char(20) NOT NULL,
`age` tinyint(2) NOT NULL DEFAULT '0',
`dept` varchar(16) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1
插入两条数据，其中一行带有中文字符
mysql> insert into teacher values(1,'wanlong','31','Server'),(2,'laomao','31','售后部');
Query OK, 2 rows affected, 1 warning (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 1
mysql> flush privileges;
Query OK, 0 rows affected (0.00 se
查看发现有乱码出现：
mysql> select * from teacher;
+----+---------+-----+--------+
| id | name | age | dept |
+----+---------+-----+--------+
| 1 | wanlong | 31 | Server |
| 2 | laomao | 31 | ??? |
+----+---------+-----+--------+
2 rows in set (0.00 sec)2) 如何解决乱码了
不乱码的思想：建议中英文混合的环境，选择utf-8
客户端：
set names utf8（临时生效）
修改my.cnf(永久生效）
[client]
default-character-set=utf8
服务端-库-表-程序
服务端：
[mysqld]
default-character-set=utf8（适合5.1及以前的版本）
character-set-server=utf8（适合5.5）
库：
查看数据库的编码：
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 | /application/mysql-5.5.32/share/charsets/ |
+--------------------------+-------------------------------------------+
8 rows in set (0.00 sec)
表：
查看表的编码：
mysql> show create table teacher\G;
*************************** 1. row ***************************
Table: teacher
Create Table: CREATE TABLE `teacher` (
`id` int(4) NOT NULL,
`name` char(20) CHARACTER SET latin1 NOT NULL,
`age` tinyint(2) NOT NULL DEFAULT '0',
`dept` varchar(16) CHARACTER SET latin1 DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)
ERROR:
No query specified
mysql> select * from teacher;
+----+---------+-----+--------+
| id | name | age | dept |
+----+---------+-----+--------+
| 1 | wanlong | 31 | Server |
| 2 | laomao | 31 | ??? |
| 3 | kobe | 35 | ??? |
+----+---------+-----+--------+
3 rows in set (0.00 sec)
mysql> show create table teacher\G;
*************************** 1. row ***************************
Table: teacher
Create Table: CREATE TABLE `teacher` (
`id` int(4) NOT NULL,
`name` char(20) CHARACTER SET latin1 NOT NULL,
`age` tinyint(2) NOT NULL DEFAULT '0',
`dept` varchar(16) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)
ERROR:
No query specified
修改字段的字符集：
mysql> alter table `teacher` change `dept` `dept` varchar(16) CHARACTER SET utf8 NOT NULL;
mysql> alter table `teacher` change `name` `name` char(20) CHARACTER SET utf8 NOT NULL;
mysql> show full columns from teacher;
+-------+-------------+-----------------+------+-----+---------+-------+---------------------------------+--
| Field | Type | Collation | Null | Key | Default | Extra | Privileges | C
+-------+-------------+-----------------+------+-----+---------+-------+---------------------------------+--
| id | int(4) | NULL | NO | | NULL | | select,insert,update,references |
| name | char(20) | utf8_general_ci | NO | | NULL | | select,insert,update,references |
| age | tinyint(2) | NULL | NO | | 0 | | select,insert,update,references |
| dept | varchar(16) | utf8_general_ci | NO | | NULL | | select,insert,update,references |
+-------+-------------+-----------------+------+-----+---------+-------+---------------------------------+--
4 rows in set (0.00 sec)
mysql> select * from teacher;
+----+---------+-----+--------+
| id | name | age | dept |
+----+---------+-----+--------+
| 1 | wanlong | 31 | Server |
| 2 | laomao | 31 | ??? |
| 3 | kobe | 35 | ??? |
+----+---------+-----+--------+
3 rows in set (0.00 sec)
测试再次插入带有中文字符的字段：
mysql> insert into teacher values(4,'万龙',30,'校园网'),(5,'知行',29,'华东院');
Query OK, 2 rows affected (0.01 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> select * from teacher;
+----+---------+-----+-----------+
| id | name | age | dept |
+----+---------+-----+-----------+
| 1 | wanlong | 31 | Server |
| 2 | laomao | 31 | ??? |
| 3 | kobe | 35 | ??? |
| 4 | 万龙 | 30 | 校园网 |
| 5 | 知行 | 29 | 华东院 |
+----+---------+-----+-----------+
5 rows in set (0.00 sec)3）老数据仍旧是乱码!
说明：
a）对于已有数据库想修改字符集不能直接通过“alter database kitty character set *”或者“alter table tablename character set *”，这两个命令都没有更新已有记录的字符集，而只是对新创建的表或记录生效。
b）已经有记录的字符的调整，必须先将数据导出，经过修改字符集后重新导入后才可完成
修改数据库默认编码：
“alter database kitty character set *”
4）参考解决方法：
如何更改生产MySQL数据库库表的字符集
1、导出表结构
mysqldump -uroot -predhat12345 -S /data/3306/mysql.sock --default-character-set=latin1 -d kitty>kittytable.sql
说明：-d只导表结构
2、编辑kittytable.sql，将lantin1改成utf8
可以用sed批量修改
3、确保数据库不再更新，导出所有数据
mysqldump -uroot -predhat12345 -S /data/3306/mysql.sock --quick --no-create-info --extended-insert --default-character-set=latin1 kitty>kittydata.sql
4、打开kittydata.sql，将set names latin1修改成set names utf8
5、删除原有的库表及数据（需要慎重）
6、建库
create database kitty default charset utf8;
7、创建表，执行kittytable.sql
mysql -uroot -predhat12345 -S /data/3306/mysql.sock kitty<kittytable.sql
8、导入数据
mysql -uroot -predhat12345 -S /data/3306/mysql.sock kitty<kittydata.sql5）执行SQL文件插入中文数据不乱码实战：
a、将需要更新的sql语句放到文本文件中
mysql> system cat test.sql
set names utf8;
insert into teacher values (6,'张飞',45,'商务部');b、通过source来调用sql文件
mysql> source test.sql
Query OK, 0 rows affected (0.00 sec)
Query OK, 1 row affected (0.01 sec)
mysql> select * from teacher;
+----+---------+-----+-----------+
| id | name | age | dept |
+----+---------+-----+-----------+
| 1 | wanlong | 31 | Server |
| 2 | laomao | 31 | ??? |
| 3 | kobe | 35 | ??? |
| 4 | 万龙 | 30 | 校园网 |
| 5 | 知行 | 29 | 华东院 |
| 6 | 张飞 | 45 | 商务部 |
+----+---------+-----+-----------+
6 rows in set (0.00 sec)
