mysql字符乱码
1）MySQL插入中文数据乱码问题：
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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` /*!40100 DEFAULT CHARACTER SET utf8 */ 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 kitty5）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)
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