MySQL字符集乱码总结

查看数据库编码: show create database db_name; 查看表编码: show create table tbl_name; 查看字段编码: show full columns from tbl_name; show full fields from tbl_name;

MySql 端配置

1. 修改my.ini文件 [mysql] default-character-set=utf8     说明:修改链接字符集和校对规则,它会同时设置character_set_client, character_set_connection, character_set_results

也可以修改 [mysqld] default-character-set=utf8 说明: 这里修改的是服务器的字符集和校对规则。 查看当前服务器的字符集和校对规则: mysql> show variables like 'character_set_server';    mysql> show variables like 'collation_server';

2. 修改数据库和表的字符集和校队规则。 例如: -- Create Database. drop database if exists HRDB; create database HRDB DEFAULT CHARACTER SET utf8;  # CHARSET=utf8 use HRDB;

-- 角色表 create table HR_ROLE (  ID bigint not null auto_increment, NAME varchar(20) not null unique, primary key (ID) ) ENGINE=INNODB DEFAULT CHARACTER SET utf8;  # CHARSET=utf8

查看当前数据库的字符集和校对规则: mysql> show variables like 'character_set_database';    mysql> show variables like 'collation_database';

查看表的字符集和校对规则: mysql> show create table HR_ROLE \G;

MySQL字符集终极解决方案

开源数据库MySQL从来都是中小企业构建web应用的首选,特别是和PHP配合简直就是一对黄金搭档,深受web开发人员的喜爱。但自从4.1以来MySQL加入了多字符集的支持,很多MySQL使用者发现中文居然不能使用了,显示变成了一堆乱码!以致于很多人还在使用3.24.58的老版本,最近上MySQL网站,发现居然不提供3.24版本的下载了,MySQL已经彻底放弃3.24版本了。好在我还留有一份windows版的copy,就当作纪念吧。 怎么会产生乱码现象的,怎么解决?只要翻下网上的解决方案,马上就可以得出答案:“在获得连接之后执行一句set names 'gb2312'”,但这样做的原因是什么呢?总结一下我的经验。 MySQL处理连接时,外部连接发送过来的SQL请求会根据以下顺序进行转换: character_set_client           //客户连接所采用的字符集 | character_set_connection  //MySQL连接字符集 | character_set_database    //数据库所采用的字符集(表,列) | character_set_results        //客户机显示所采用的字符集 一. 产生乱码的根本原因在于: 1.客户机没有正确地设置client字符集,导致原先的SQL语句被转换成connection所指字符集,而这种转换,是会丢失信息的,如果client是utf8格式,那么如果转换成gb2312格式,这其中必定会丢失信息,反之则不会丢失。一定要保证connection的字符集大于client字符集才能保证转换不丢失信息。 2. 数据库字体没有设置正确,如果数据库字体设置不正确,那么connection字符集转换成database字符集照样丢失编码,原因跟上面一样。 二.为什么set names 'gb2312'就可以了呢 set names 'gb2312'相当于这三条语句: set character_set_client = gb2312; set character_set_connection = gb2312; set character_set_results = gb2312; 这样做的话,上述产生乱码的原因1就不存在了,因为编码格式都统一了,但是这样做并不是万金油。原因有: 1.你的client不一定是用gb2312编码发送SQL的,如果编码不是gb2312那么转换成gb2312就会产生问题。 2.你的数据库中的表不一定是gb2312格式,如果不是gb2312格式而是其他的比如说latin1,那么在存储字符集的时候就会产生信息丢失。 综上,终极解决方案如下: 1.首先要明确你的客户端时候何种编码格式,这是最重要的(IE6一般用utf8,命令行一般是gbk,一般程序是gb2312) 2.确保你的数据库使用utf8格式,很简单,所有编码通吃。 3.一定要保证connection字符集大于等于client字符集,不然就会信息丢失,比如: latin1 < gb2312 < gbk < utf8,若设置set character_set_client = gb2312,那么至少connection的字符集要大于等于gb2312,否则就会丢失信息 4.以上三步做正确的话,那么所有中文都被正确地转换成utf8格式存储进了数据库,为了适应不同的浏览器,不同的客户端,你可以修改character_set_results来以不同的编码显示中文字体,由于utf8是大方向,因此web应用是我还是倾向于使用utf8格式显示中文的。 以上就是我的心得了。附上连接源码,现行设置,程序中就可以不考虑字符集问题了 include "conf/system.php"; class Connection { private $conn; function __construct() { global $mysql_ipaddr, $mysql_port, $mysql_db, $mysql_user, $mysql_pass; try { $this->conn = new PDO("mysql:host=$mysql_ipaddr;port=$mysql_port;dbname=$mysql_db", $mysql_user, $mysql_pass); } catch (PDOException $e) { print "MySQL服务器连接失败: " . $e->getMessage() . "<br>"; die(); } } public function getConnection() { if ($this->conn != null) { $this->conn->query("set character_set_client = gb2312");    //客户端使用gb2312格式 $this->conn->query("set character_set_connection = utf8"); //连接字符集使用utf8格式 $this->conn->query("set character_set_results = utf8");       //显示字符集使用utf8格式 return $this->conn; } } public function closeConnection() { if ($this->conn != null) { $this->conn = null; } } }

Q: 在写一个查询条件时的问题:如我想写一个字段中包含“李”字的所有记录 $str="李"; select * from table where field like '%$str%' ;

显示的记录中除了包含”李”字的记录,还有不包含“李”字的记录。为什么?

A: 在MySQL中,进行中文排序和查找的时候,对汉字的排序和查找结果是错误的。这种情况在MySQL的很多版本中都存在。如果这个问题不解决,那么MySQL将无法实际处理中文。 出现这个问题的原因是:MySQL在查询字符串时是大小写不敏感的,在编绎MySQL时一般以ISO-8859字符集作为默认的字符集,因此在比较过程中中文编码字符大小写转换造成了这种现象。

现在mysql上遇到一个问题,我们的字符集是gb2312.在中文模糊查找时,会有不相关的结果集.

从问题的根本原因分析,还有下面的问题。例: 汉字“不”的第1、2字节ascii值分别为:178与187 汉字“安”的第1、2字节ascii值分别为:176与178 汉字“花”的第1、2字节ascii值分别为:187与168 聪明的人已经看出来了:在字符串“安花”中模糊查找字符“不”字时,mysql系统也会认为两者匹配!

出现这个问题的原因是:MySQL在查询字符串时是大小写不敏感的,在编绎MySQL时一般以ISO-8859字符集作为默认的字符集,因此在比较过程中中文编码字符大小写转换造成了这种现象。 方法一: 解决方法是对于包含中文的字段加上"binary"属性,使之作为二进制比较,例如将"name char(10)"改成"name char(10)binary"。 方法二: 如果你使用源码编译MySQL,可以编译MySQL时使用--with--charset=gbk 参数,这样MySQL就会直接支持中文查找和排序了。 方法三: 可以使用 Mysql 的 locate 函数来判断。以上述问题为例,使用方法为: SELECT * FROM table WHERE locate(field,'李') > 0; 本站使用的就是这种方法,感觉还不错。:P 方法四: 把您的Select语句改成这样,SELECT * FROM TABLE WHERE FIELDS LIKE BINARY '%FIND%'即可!

升级的根本,如果想使用“正确”的字符集,还是先用mysqldump导出成文件,然后导入。

--------------------------------------------------------------------------------------------------------------------------------------

MySQL 字符集查询

1) status

mysql> status;
--------------
mysql  Ver 14.14 Distrib 5.1.54, for debian-linux-gnu (x86_64) using readline 6.2

Connection id:		74267
Current database:	
Current user:		root@localhost
SSL:			Not in use
Current pager:		stdout
Using outfile:		''
Using delimiter:	;
Server version:		5.5.16-log Source distribution
Protocol version:	10
Connection:		Localhost via UNIX socket
Server characterset:	latin1
Db     characterset:	latin1
Client characterset:	latin1
Conn.  characterset:	latin1
UNIX socket:		/var/run/mysqld/mysqld.sock
Uptime:			128 days 13 hours 4 min 59 sec

Threads: 1  Questions: 356155  Slow queries: 2  Opens: 3975  Flush tables: 1  Open tables: 256  Queries per second avg: 0.032
--------------

2)show variables like 'collation_%';

mysql> show variables like 'collation_%';
+----------------------+-------------------+
| Variable_name        | Value             |
+----------------------+-------------------+
| collation_connection | utf8_general_ci   |
| collation_database   | latin1_swedish_ci |
| collation_server     | latin1_swedish_ci |
+----------------------+-------------------+

3)show variables like 'character_%'; 

mysql> show variables like 'character_%';
+--------------------------+----------------------------+
| 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     | latin1                     |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+

4) show create table table_name;

mysql> show create table t1;
+-------+------------------------------------
| Table | Create Table                       
+-------+------------------------------------
| t1    | CREATE TABLE `t1` (
  `id` int(11) NOT NULL,
  `c1` varchar(30) DEFAULT NULL,
  PRIMARY KEY (`id`)    
) ENGINE=InnoDB DEFAULT CHARSET=gbk |
+-------+------------------------------------
1 row in set (0.00 sec) 
                        
mysql> show full columns from t1;
+-------+-------------+----------------+------+-----+-
| Field | Type        | Collation      | Null | Key | 
+-------+-------------+----------------+------+-----+-
| id    | int(11)     | NULL           | NO   | PRI | 
| c1    | varchar(30) | gbk_chinese_ci | YES  |     | 
+-------+-------------+----------------+------+-----+-

5) show full fields from table_name;

mysql> show full fields from user_info;
+------------+-------------+-------------------+------+-----+---------+-------+---------------------------------+---------+
| Field      | Type        | Collation         | Null | Key | Default | Extra | Privileges                      | Comment |
+------------+-------------+-------------------+------+-----+---------+-------+---------------------------------+---------+
| uid        | bigint(18)  | NULL              | NO   |     | NULL    |       | select,insert,update,references |         |
| mac_id     | char(17)    | latin1_swedish_ci | NO   |     | NULL    |       | select,insert,update,references |         |
| name       | varchar(50) | latin1_swedish_ci | YES  |     | NULL    |       | select,insert,update,references |         |
| nickname   | varchar(50) | latin1_swedish_ci | YES  |     | NULL    |       | select,insert,update,references |         |
| gender     | tinyint(1)  | NULL              | YES  |     | 0       |       | select,insert,update,references |         |
| age        | varchar(7)  | latin1_swedish_ci | YES  |     | NULL    |       | select,insert,update,references |         |
+------------+-------------+-------------------+------+-----+---------+-------+---------------------------------+---------+

6)查看mysql支持的字符集: show charset;  或 show char set;

mysql> show charset;
+----------+-----------------------------+---------------------+--------+
| 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 |
+----------+-----------------------------+---------------------+--------+

MySQL 字符集修改

MySQL中默认字符集的设置有四级:服务器级,数据库级,表级 ,字段级。注意前三种均为默认设置,并不代表你的字段最终会使用这个字符集设置。

MySQL中关于连接环境的字符集设置有 Client端,connection,results 通过这些参数,MySQL就知道你的客户端工具用的是什么字符集,结果集应该是什么字符集。这样MySQL就会做必要的翻译,一旦这些参数有误,自然会导致字符串在转输过程中的转换错误。基本上99%的乱码由些造成。

0) 查看默认数据库集: status

mysql> status;
--------------
mysql  Ver 14.14 Distrib 5.5.31, for debian-linux-gnu (x86_64) using readline 6.2

Connection id:		41
Current database:	tvbss_01
Current user:		root@localhost
SSL:			Not in use
Current pager:		stdout
Using outfile:		''
Using delimiter:	;
Server version:		5.5.31-0ubuntu0.12.04.1 (Ubuntu)
Protocol version:	10
Connection:		Localhost via UNIX socket
Server characterset:	latin1
Db     characterset:	latin1
Client characterset:	utf8
Conn.  characterset:	utf8
UNIX socket:		/var/run/mysqld/mysqld.sock
Uptime:			7 min 30 sec

Threads: 1  Questions: 131  Slow queries: 0  Opens: 239  Flush tables: 1  Open tables: 58  Queries per second avg: 0.291
--------------

说明: 通过 sudo apt-get install mysql-server 安装的mysql,默认client和conn为utf8编码,server和db为latin1编码,修改client和conn编码请继续下看。

修改客户端,服务器级,数据库级方法如下:

(1) 使用超级用户root权限,打开 /etc/mysql/my.cnf 

root@ubuntu:/# vi /etc/mysql/my.cnf        

(2) 修改客户端级,在 [client] 下添加一行:default-character-set=utf8

[client]
default-character-set=utf8
port		= 3306
socket		= /var/run/mysqld/mysqld.sock

如果想修改client和conn为latin1,只需把utf8改为latin1,更多编码格式请见下面:show charset;

(3) 修改服务器级,在 [mysqld] 添加两行: character-set-server=utf8    和   collation-server=utf8_general_ci

[mysqld]
character-set-server=utf8
collation-server=utf8_general_ci
#
# * Basic Settings
#
user		= mysql
pid-file	= /var/run/mysqld/mysqld.pid
socket		= /var/run/mysqld/mysqld.sock

status 查询结果发现: Server 和 Db  变成了 utf8

mysql> status;
--------------
mysql  Ver 14.14 Distrib 5.5.31, for debian-linux-gnu (x86_64) using readline 6.2

Connection id:		42
Current database:	
Current user:		root@localhost
SSL:			Not in use
Current pager:		stdout
Using outfile:		''
Using delimiter:	;
Server version:		5.5.31-0ubuntu0.12.04.1 (Ubuntu)
Protocol version:	10
Connection:		Localhost via UNIX socket
Server characterset:	utf8
Db     characterset:	utf8
Client characterset:	utf8
Conn.  characterset:	utf8
UNIX socket:		/var/run/mysqld/mysqld.sock
Uptime:			19 sec

Threads: 1  Questions: 130  Slow queries: 0  Opens: 239  Flush tables: 1  Open tables: 58  Queries per second avg: 6.842
--------------

collation 和 character 查询结果发现: collation_server 和 character_set_server 也都变成了 utf8 

mysql> show variables like 'character_%';
+--------------------------+----------------------------+
| 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       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+

mysql> show variables like 'collation_%';
+----------------------+-----------------+
| Variable_name        | Value           |
+----------------------+-----------------+
| collation_connection | utf8_general_ci |
| collation_database   | utf8_general_ci |
| collation_server     | utf8_general_ci |
+----------------------+-----------------+

(4)修改数据库字符集的两种方法

           a)修改db.opt文件: vi /var/lib/mysql/your_dbname/db.opt           # your_dbname是自己数据库的名称

default-character-set=latin1
default-collation=latin1_swedish_ci

修改为:

default-character-set=utf8
default-collation=utf8_general_ci

                   修改后发现:Db     characterset 变为了 utf8

mysql> status;
--------------
mysql  Ver 14.14 Distrib 5.5.31, for debian-linux-gnu (x86_64) using readline 6.2

Connection id:		42
Current database:	tvbss_01
Current user:		root@localhost
SSL:			Not in use
Current pager:		stdout
Using outfile:		''
Using delimiter:	;
Server version:		5.5.31-0ubuntu0.12.04.1 (Ubuntu)
Protocol version:	10
Connection:		Localhost via UNIX socket
Server characterset:	latin1
Db     characterset:	utf8
Client characterset:	utf8
Conn.  characterset:	utf8
UNIX socket:		/var/run/mysqld/mysqld.sock
Uptime:			1 min 22 sec

Threads: 1  Questions: 142  Slow queries: 0  Opens: 239  Flush tables: 1  Open tables: 58  Queries per second avg: 1.731
--------------

           b)命令行修改:  mysql> use your_dbname;    mysql> alter database your_dbname character set utf8;     结果同上。且此时命令行也修改了 /var/lib/mysql/your_dbname/db.opt 文件的编码为utf8(同方法a)

MySQL 表、字段的字符集修改

1) 修改表的字符集: ALTER TABLE tbl_name CONVERT TO CHARACTER SET character_name [COLLATE utf8_general_ci]

修改表字符集示例: 数据库表 tbl_name 从latin1 转为 utf8 

mysql> show create table db_name.tbl_name;
+------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| user_info | CREATE TABLE `user_info` (
  `uid` bigint(18) NOT NULL,
  `name` varchar(50) DEFAULT NULL,
  `nickname` varchar(50) DEFAULT NULL,
  `gender` tinyint(1) DEFAULT '0',
  `age` varchar(7) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-----------

mysql> alter table table db_name.tbl_name convert to character set utf8 collate utf8_general_ci;

mysql> show create table db_name.tbl_name;
+------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| user_info | CREATE TABLE `user_info` (
  `uid` bigint(18) NOT NULL,
  `name` varchar(50) DEFAULT NULL,
  `nickname` varchar(50) DEFAULT NULL,
  `gender` tinyint(1) DEFAULT '0',
  `age` varchar(7) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |

2)修改表的字段字符集: ALTER TABLE tbl_name CHANGE column_name column_name CHARACTER SET character_name [COLLATE utf8_general_ci...];

修改表的字段字符集示例:   字段 name 从 utf8 转为 latin1

mysql> show full fields from db_name.tbl_name;
+------------+-------------+-----------------+------+-----+---------+-------+---------------------------------+---------+
| Field      | Type        | Collation       | Null | Key | Default | Extra | Privileges                      | Comment |
+------------+-------------+-----------------+------+-----+---------+-------+---------------------------------+---------+
| uid        | bigint(18)  | NULL            | NO   |     | NULL    |       | select,insert,update,references |         |
| name       | varchar(50) | utf8_general_ci | YES  |     | NULL    |       | select,insert,update,references |         |
| nickname   | varchar(50) | utf8_general_ci | YES  |     | NULL    |       | select,insert,update,references |         |
| gender     | tinyint(1)  | NULL            | YES  |     | 0       |       | select,insert,update,references |         |
| age        | varchar(7)  | utf8_general_ci | YES  |     | NULL    |       | select,insert,update,references |         |
+------------+-------------+-----------------+------+-----+---------+-------+---------------------------------+---------+

mysql> alter table db_name.tbl_name change name name varchar(50) character set latin1 collate latin1_swedish_ci;

mysql> show full fields from db_name.tbl_name;
+------------+-------------+-------------------+------+-----+---------+-------+---------------------------------+---------+
| Field      | Type        | Collation         | Null | Key | Default | Extra | Privileges                      | Comment |
+------------+-------------+-------------------+------+-----+---------+-------+---------------------------------+---------+
| uid        | bigint(18)  | NULL              | NO   |     | NULL    |       | select,insert,update,references |         |
| name       | varchar(50) | latin1_swedish_ci | YES  |     | NULL    |       | select,insert,update,references |         |
| nickname   | varchar(50) | utf8_general_ci   | YES  |     | NULL    |       | select,insert,update,references |         |
| gender     | tinyint(1)  | NULL              | YES  |     | 0       |       | select,insert,update,references |         |
| age        | varchar(7)  | utf8_general_ci   | YES  |     | NULL    |       | select,insert,update,references |         |
+------------+-------------+-------------------+------+-----+---------+-------+---------------------------------+---------+

MySQL 连接数

1) 查看连接数

show variables like "max_connections";

+-----------------+-------+ | Variable_name   | Value | +-----------------+-------+ | max_connections | 500   | +-----------------+-------+

2) 修改连接数(命令)

set global max_connections = 200;

+-----------------+-------+ | Variable_name   | Value | +-----------------+-------+ | max_connections | 200   | +-----------------+-------+

不用重启就生效

3) 修改连接数(配置文件)

sudo vi /etc/mysql/my.cnf

1)去掉注释,修改为: max_connections = 200

2) 重启MySQL生效

参考推荐:

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第10章:字符集支持(MySQL官方,推荐)

设置mysql字符集为utf8(ITeye,推荐)

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How to update the max_connections setting in MySQL

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