8、mysql乱码问题及字符集实战
8.1、mysql插入中文数据乱码案例:
mysql建库的字符集为latin1,客户端的字符集为utf8;
use lc;
1、查看库的编码:
mysql> show create database lc\G;
*************************** 1. row ***************************
Database: lc
Create Database: CREATE DATABASE `lc` /*!40100 DEFAULT CHARACTER SET latin1 */
2、查看表的编码:
表的字符集默认是根据库来的;
mysql> show create table test\G;
*************************** 1. row ***************************
Table: test
Create Table: CREATE TABLE `test` (
`id` int(4) NOT NULL AUTO_INCREMENT,
`name` varchar(20) NOT NULL COMMENT '姓名',
`age` varchar(2) DEFAULT NULL COMMENT '年龄',
PRIMARY KEY (`id`),
KEY `index_name` (`name`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=latin1
3、插入数据:
mysql> insert into test (name) values ('刘畅');
mysql> select * from test;
+----+------+------+
| id | name | age |
+----+------+------+
| 1 | lc | 20 |
| 2 | lc2 | 21 |
| 3 | lc3 | 22 |
| 4 | lc4 | 23 |
| 5 | lc | 22 |
| 6 | ?? | NULL |
+----+------+------+
4、解决乱码:
(1)为什么会出现乱码的情况:
因为系统(软件)使用的字符集和表使用的字符集不匹配,所以会乱码;
(2)解决方法一(临时生效):
[root@db01 ~]# mysql -uroot -p123456
mysql> use lc;
mysql> set names latinl; #使系统的编码为latinl;
mysql> insert into test (name) values ('刘畅');
mysql> select * from test; #设置字符集为插入数据表的字符集,然后在插入中文语句测试;
+----+--------+------+
| id | name | age |
+----+--------+------+
| 1 | lc | 20 |
| 2 | lc2 | 21 |
| 3 | lc3 | 22 |
| 4 | lc4 | 23 |
| 5 | lc | 22 |
| 6 | ?? | NULL |
| 7 | 刘畅 | NULL |
+----+--------+------+
(3)解决方法二(临时生效):
用于批量插入数据时使用;
[root@db01 ~]# vim test.sql;
set names latin1;
insert into test(name) values(刘畅1);
1)
[root@db01 ~]# mysql -uroot -p123456 lc </root/test.sql
[root@db01 ~]# mysql -uroot -p123456
mysql> use lc;
mysql> set names latin1; #用于查看数据;
2)
[root@db01 ~]# mysql -uroot -p123456
mysql> use lc;
mysql> source /root/test.sql;
mysql> set names latin1; #用于查看数据;
(4)解决方法三(临时生效):
[root@db01 ~]# mysql -uroot -p123456 --default-character-set=latin1
mysql> use lc;
mysql> insert into test (name) values ('刘畅3');
(5)解决方法四(永久生效):
编译的时候指定字符集;
-DDEFAULT_CHARSET=utf8 \
-DDEFAULT_COLLATION=utf8_general_ci \
建库的时候指定字符集;
show character set; #查看系统支持的字符集
create database lc1 default character set gbk collate gbk_chinese_ci; #指定gbk字符集;
create database lc2 default character set utf8 collate utf8_general_ci; #指定utf8字符集;
建表的时候指定字符集:
Create Table: CREATE TABLE `student` (
`id` int(16) NOT NULL,
`name` varchar(20) NOT NULL,
`age` int(2) NOT NULL,
`dept` varchar(20) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
修改my.cnf配置文件;
[client]
default-character-set=utf8 #不需要重启mysql服务,客户端;
[mysqld]
character-set-server=utf8 #需要重启mysql服务,服务端;
5、小结:
改字符集分为该客户端和服务端两种;
(1)客户端(不需要重启mysql服务):
1)dql,dml语句之前加‘set names <字符编码类型> ’的语句;
2)mysql -uroot -p123456 --default-character-set=latin1
mysqldump -uroot -p123456 --default-character-set=latin1 -B lc >/tmp/lc.sql
3)修改my.cnf;
[client]
default-character-set=utf8
4)vim /etc/sysconfig/i18n
注意:修改scrt连接器的编码和linux系统一致,my.cnf的优先级高于/etc/sysconfig/i18n配置的优先级;
(2)服务端:
1)编译时指定字符集;
2)建库时指定字符集;
3)建表时指定字符集;
4)在my.cnf中配置:
[mysqld]
character-set-server=utf8 #需要重启mysql服务,目的是将配置放到内存中,效率最快;
(3)生效问题:
(1)中的1)2)临时生效,3)4)永久生效;
(2)中的1)2)3)4)都是永久的生效;
(4)注意以上的方法客户端和服务端任意取其一配对就可,推荐使用utf8;
8.2、字符集深入讲解:
1、介绍:
2、常见的字符集:
3、如何选择合适的字符集:
4、如何查看mysql的字符集:
[root@db01 ~]# mysql -uroot -p123456 -e "show character set;"
字符集 描述 校对规则 最大长度
+----------+-----------------------------+---------------------+--------+
| 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 |
+----------+-----------------------------+---------------------+--------+
5、查看mysql当前系统字符的设置:
(1)mysql建库的字符集是latin1:
1) 客户端是utf8中文:
[root@db01 ~]# vim /etc/sysconfig/i18n
LANG=zh_CN.UTF8
[root@db01 ~]# mysql -uroot -p123456 -e "show variables like 'character_set%'"
+--------------------------+-------------------------------------------+
| Variable_name | Value |
+--------------------------+-------------------------------------------+
| character_set_client | utf8 #客户端字符集; |
| character_set_connection | utf8 #连接字符集; |
| character_set_database | latin1 #数据库字符集,配置文件指定或建库时指定; |
| character_set_filesystem | binary |
| character_set_results | utf8 #返回结果字符集; |
| character_set_server | latin1 #服务器字符集,配置文件;|
| character_set_system | utf8 |
| character_sets_dir | /application/mysql-5.5.62/share/charsets/ |
+--------------------------+-------------------------------------------+
2)客户端是英文:
[root@db01 ~]# vim /etc/sysconfig/i18n
LANG=en
[root@db01 ~]# mysql -uroot -p123456 -e "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/mysql-5.5.62/share/charsets/ |
+--------------------------+-------------------------------------------+
(2)mysql建库字符集是utf8:
[root@db01 ~]# vim /etc/my.cnf #修改mysql的配置文件;
[mysqld]
character-set-server=utf8
[root@db01 ~]# /etc/init.d/mysqld restart
[root@db01 ~]# vim /etc/sysconfig/i18n
LANG=zh_CN.UTF8
[root@db01 ~]# mysql -uroot -p123456 -e "show variables like 'character_set%';"
+--------------------------+-------------------------------------------+
| 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-5.5.62/share/charsets/ |
+--------------------------+-------------------------------------------+
(3)实验:
mysql建库,客户端的字符集都是utf8;lc库和表编码是latin1,里面有latin1编码的数据;
mysql> use lc;
Database changed
mysql> select * from test;
+----+-----------------+------+
| id | name | age |
+----+-----------------+------+
| 1 | lc | 20 |
| 2 | lc2 | 21 |
| 3 | lc3 | 22 |
| 4 | lc4 | 23 |
| 5 | lc | 22 |
| 6 | ?? | NULL |
| 8 | 刘畅 | NULL |
| 9 | 刘畅1 | NULL |
| 10 | 刘畅2 | NULL |
| 12 | 刘畅3 | NULL |
| 14 | çš„ | NULL |
+----+-----------------+------+
mysql> show variables like 'character_set%';
+--------------------------+-------------------------------------------+
| Variable_name | Value |
+--------------------------+-------------------------------------------+
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | latin1 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | utf8 |
| character_set_system | utf8 |
| character_sets_dir | /application/mysql-5.5.62/share/charsets/ |
+--------------------------+-------------------------------------------+
8 rows in set (0.00 sec)
mysql> set names latin1;
Query OK, 0 rows affected (0.00 sec)
mysql> select * from test;
+----+---------+------+
| id | name | age |
+----+---------+------+
| 1 | lc | 20 |
| 2 | lc2 | 21 |
| 3 | lc3 | 22 |
| 4 | lc4 | 23 |
| 5 | lc | 22 |
| 6 | ?? | NULL |
| 8 | 刘畅 | NULL |
| 9 | 刘畅1 | NULL |
| 10 | 刘畅2 | NULL |
| 12 | 刘畅3 | NULL |
| 14 | 的 | NULL |
+----+---------+------+
11 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 | /application/mysql-5.5.62/share/charsets/ |
+--------------------------+-------------------------------------------+
8 rows in set (0.00 sec)
(4)总结:
1)字符集在实际的环境中客户端和服务端要统一;
2)character_set_client,character_set_connection,character_set_results三者的字符集和系统
的字符集一致,属于客户端字符集,即为/etc/sysconfig/i18n文件中设置的字符集,可以使用
echo $LANG进行查看系统的字符集,也可以对my.cnf [client] default-character-set=utf8进行
修改(无需重启mysql服务),my.cnf的优先级高于/etc/sysconfig/i18n配置的优先级,由(1)得到。
永久生效;
3)character_set_server,character_set_database是mysql建库字符集,即服务端的字符集,可以
在编译mysql时指定,也可以在在my.cnf中通过[mysqld] character-set-server=utf8(重启mysql)参数来指定;
永久生效,由(2)得到,需要注意的是mysql中的mysql等默认库会根据服务编码的改变而变化;
4)如果别人已经指定好了字符集对库和表,而客户端的字符集不同,需要使用set nams <字符集>
语句或mysql -uroot -p123456 --default-character-set,
mysql -uroot -p123456 --default-character-set=latin1 -B lc >/tmp/lc.sql,临时生效;
更改/etc/sysconfig/i18或修改my.cnf文件 "[client] default-character-set=utf8"(注意:修改scrt连接器的编码
和linux系统一致)永久生效;
5)库表的字符集要和要和客户端的字符集统一,这个最为重要,虽然服务端和客户端编码一致,但是建库建表时
不一致也会导致乱码的情况,由(3)得到;
6)开发的程序也属于客户端,需要和库表的字符集一致;
7)杜绝数据库中多库不同编码的用法,虽然说,只要客户端和库表的编码一致就不会出现问题,但是这样做不规范应该
保持客户端-服务端-库-表编码的一致性,工作中推荐使用utf8编码;
8.3、数据字符集修改的步骤:
对于已有数据库想修改字符集,不能直接通过“alter database character set *”或通过“alter table 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,旧的记录不生效;
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以完成。
1、说明:
mysql建库,客户端的字符集都是utf8;lc库和表编码是latin1,里面有latin1编码的数据;
1、停止数据库对外的访问,并对库进行备份:
(1)停止数据库对外的访问,确保数据库不再更新;
(2)对原有的库进行备份:
mysqldump -uroot -p123456 --default-character-set=latin1 -F -R -B lc >/tmp/lc_bak.sql
#--default-character-set=latin1:表示客户端使用latin1进行连接数据库,这样导出的数据不会乱码;
2、导出表结构修改为utf8:
mysqldump -uroot -p123456 --default-character-set=latin1 -F -d lc >/tmp/lc_table_all.sql
#-d:表示指导出表结构;
sed -i "s#latin1#utf8#g" /tmp/lc_table_all.sql
3、导出数据库中的的所有数据:
mysqldump -uroot -p123456 --quick --no-create-info --extended-insert --default-character-set=latin1 -F lc >/tmp/lc_data_all.sql
#--quick:用于转储大的表,强制mysqldump从服务器一次一行的检索数据而不是检索所有行,并输出到cache到内存中;
#--no-create-info:不创建create table语句;
#--extended-insert:使用包括几个values列的多行insert语法,这样导出的文件中,所有的中文都是可见的,不会保存成乱码;
sed -i "s#latin1#utf8#g" /tmp/lc_data_all.sql
4、删除原来的数据库:
mysql -uroot -p123456
mysql> drop database lc;
5、导入数据库的表和数据:
(1)新建库:
mysql> create database lc default character set utf8 collate utf8_general_ci;
mysql> exit;
(2)导入表结构:
mysql -uroot -p123456 lc </tmp/lc_table_all.sql
(3)导入数据:
mysql -uroot -p123456 lc </tmp/lc_data_all.sql
6、总结:
(1)转存的数据会保存为当前的客户端编码,不会乱码;
(1)对数据库进行备份后可以直接使用sed命令修改latin1为utf8,然后从第4步骤开始在进行还原的一系
列操作,省去了导表结构和表数据的步骤,亲测是可以用的;