乱码产生原因
mysql字符编码是版本4.1引入的,支持多国语言,而且一些特性已经超过了其他的数据库系统。
我们可以在MySQL Command Line Client 下输入如下命令查看mysql的字符集
mysql> SHOW CHARACTER SET;
+----------+-----------------------------+---------------------+--------+
| 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 |
| cp1251 | Windows Cyrillic | cp1251_general_ci | 1 |
| cp1256 | Windows Arabic | cp1256_general_ci | 1 |
| cp1257 | Windows Baltic | cp1257_general_ci | 1 |
| 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 |
+----------+-----------------------------+---------------------+--------+
36 rows in set (0.02 sec)
更多mysql的字符集知识可以参考本论坛的
http://www.phpfans.net/bbs/viewt ... &extra=page%3D1
或者mysql官方的
http://dev.mysql.com/doc/refman/5.1/zh/charset.html
MySQL 4.1的字符集支持(Character Set Support)有两个方面：字符集(Character set)和排序方式(Collation)。对于字符集的支持细化到四个层次: 服务器(server)，数据库(database)，数据表(table)和连接(connection)。
查看系统的字符集和排序方式的设定可以通过下面的两条命令：
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 | latin1 |
| character_set_system | utf8 |
| character_sets_dir | D:\MySQL\MySQL Server 5.0\share\charsets\ |
+--------------------------+-------------------------------------------+
8 rows in set (0.06 sec)
mysql> SHOW VARIABLES LIKE 'collation_%';
+----------------------+-------------------+
| Variable_name | Value |
+----------------------+-------------------+
| collation_connection | latin1_swedish_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
+----------------------+-------------------+
3 rows in set (0.02 sec)
上面列出的值就是系统的默认值。latin1默认校对规则是latin1_swedish_ci，默认是latin1的瑞典语排序方式.
为什么呢默认会是latin1_swedish_ci呢,追溯一下mysql历史很容易发现
1979年，一家瑞典公司Tcx欲开发一个快速的多线程、多用户数据库系统。Tcx 公司起初想利用mSQL和他们自己的快速低级例程 (Indexed Sequential Access Method，ISAM)去连接数据库表，然而，在一些测试以后得出结论：mSQL对其需求来说不够快速和灵活。这就产生了一个连接器数据库的新SQL接口，它使用几乎和mSQL一样的API接口。这个API被设计成可以使那些由mSQL而写的第三方代码更容易地移植到MySQL。
相信如果mysql是中国开发的，那么汉语也是默认编码了
当然我们也可以自己需要修改mysql的默认字符集
在mysql配置文档my.ini，找到如下两句：
[mysql]
default-character-set=latin1
和
# created and no character set is defined
default-character-set=latin1
修改后面的值就可以。
这里不建议改，仍保留默认值
也就是说启动 mysql时，如果没指定指定一个默认的的字符集，这个值继承自配置文件中的；
此时 character_set_server 被设定为这个默认的字符集； 当创建一个新的数据库时，
除非明确指定，这个数据库的字符集被缺省设定为 character_set_server； 当选定了一个数据库时，
character_set_database 被设定为这个数据库默认的字符集； 在这个数据库里创建一张表时，
表默认的字符集被设定为 character_set_database，也就是这个数据库默认的字符集；
当在表内设置一栏时，除非明确指定，否则此栏缺省的字符集就是表默认的字符集。
这样问题就随之而来了，假如一数据库是gbk编码。如果访问数据库时没指定其的字符集是gbk。
那么这个值将继承系统的latin1，这样就做成mysql中文乱码。
乱码解决方法
要解决乱码问题，首先必须弄清楚自己数据库用什么编码。如果没有指明，将是默认的latin1。
我们用得最多的应该是这3种字符集 gb2312，gbk，utf8。
那么我们如何去指定数据库的字符集呢？下面也gbk为例
【在MySQL Command Line Client创建数据库 】
mysql> CREATE TABLE `mysqlcode` (
-> `id` TINYINT( 255 ) UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY ,
-> `content` VARCHAR( 255 ) NOT NULL
-> ) TYPE = MYISAM CHARACTER SET gbk COLLATE gbk_chinese_ci;
Query OK, 0 rows affected, 1 warning (0.03 sec)
mysql> desc mysqlcode;
+---------+-----------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+-----------------------+------+-----+---------+----------------+
| id | tinyint(255) unsigned | NO | PRI | | auto_increment |
| content | varchar(255) | NO | | | |
+---------+-----------------------+------+-----+---------+----------------+
2 rows in set (0.02 sec)
其中后面的TYPE = MYISAM CHARACTER SET gbk COLLATE gbk_chinese_ci;
就是指定数据库的字符集，COLLATE (校勘)，让mysql同时支持多种编码的数据库。
当然我们也可以通过如下指令修改数据库的字符集
alter database da_name default character set 'charset'.
php爱好者站 http://www.phpfans.net
客户端以 gbk格式发送 ，可以采用下述配置:
SET character_set_client='gbk'
SET character_set_connection='gbk'
SET character_set_results='gbk'
这个配置就等价于 SET NAMES 'gbk'。
现在对刚才创建的数据库操作
mysql> use test;
Database changed
mysql> insert into mysqlcode values(null,'php爱好者');
ERROR 1406 (22001): Data too long for column 'content' at row 1
没有指定字符集为gbk，插入时出错
mysql> set names 'gbk';
Query OK, 0 rows affected (0.02 sec)
指定字符集为 gbk
mysql> insert into mysqlcode values(null,'php爱好者');
Query OK, 1 row affected (0.00 sec)
插入成功
mysql> select * from mysqlcode;
+----+-----------+
| id | content |
+----+-----------+
| 1 | php爱好着 |
+----+-----------+
1 row in set (0.00 sec)
在没有指定字符集gbk时读取也会出现乱码，如下
mysql> select * from mysqlcode;
+----+---------+
| id | content |
+----+---------+
| 1 | php??? |
+----+---------+
1 row in set (0.00 sec)
【在phpmyadmin创建数据库,并指定字符集】
screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onmousewheel="return imgzoom(this);" onclick="if(!this.resized) {return true;} else {window.open('/upload/20070902220747172.jpg');}" border=0 alt="" align=center src="http://files.glzy8.com/upload/20070902220747172.jpg" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}">
表类型根据自己需要选，这里选MyISAM(非事务);
整理选择 gbk_chinese_ci 也就是gbk字符集
gbk_bin 简体中文, 二进制。gbk_chinese_ci 简体中文, 不区分大小写。
在刚才创建的数据库插入数据库
screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onmousewheel="return imgzoom(this);" onclick="if(!this.resized) {return true;} else {window.open('/upload/20070902220747434.jpg');}" border=0 alt="" align=center src="http://files.glzy8.com/upload/20070902220747434.jpg" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}">
再浏览时发现是乱码
screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onmousewheel="return imgzoom(this);" onclick="if(!this.resized) {return true;} else {window.open('/upload/20070902220748695.jpg');}" border=0 alt="" align=center src="http://files.glzy8.com/upload/20070902220748695.jpg" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}">
为什么呢？是因为数据库为gbk字符集，而我们操作时没有指定为gbk
回到数据库首页
screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onmousewheel="return imgzoom(this);" onclick="if(!this.resized) {return true;} else {window.open('/upload/20070902220748346.jpg');}" border=0 alt="" align=center src="http://files.glzy8.com/upload/20070902220748346.jpg" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}">
可以看到 mysql 连接校对默认的latin1_bin。我们将其改为gbk_chinese_ci
screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onmousewheel="return imgzoom(this);" onclick="if(!this.resized) {return true;} else {window.open('/upload/20070902220748318.jpg');}" border=0 alt="" align=center src="http://files.glzy8.com/upload/20070902220748318.jpg" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}">
再插入一条数据。看，这条已经正常了
screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onmousewheel="return imgzoom(this);" onclick="if(!this.resized) {return true;} else {window.open('/upload/20070902220748356.jpg');}" border=0 alt="" align=center src="http://files.glzy8.com/upload/20070902220748356.jpg" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}">
【解决php读取数据库乱码】
仍以数据库mysqlcode为例
<?php
//php爱好者站教程 http://www.phpfans.net
$conn = mysql_connect("localhost","root","");
mysql_query("set names 'gbk'");//这就是指定数据库字符集，一般放在连接数据库后面就系了
mysql_select_db("test");
$sql = "select * from mysqlcode";
$result = mysql_query($sql,$conn);
?>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>mysql 字符编码</title>
</head>
<body>
<table width="300" height="32" border="1" align="center" cellpadding="0" cellspacing="0">
<tr>
<td width="71" align="center">id</td>
<td width="229" align="center">内容</td>
</tr>
<?php while($row = mysql_fetch_assoc($result)){
echo "
<tr>
<td align=\"center\">".$row['id']."</td>
<td>".$row['content']."</td>
</tr>";
}?>
</table>
</body>
</html>
<?php mysql_free_result($result);?>
如果我们将mysql_query("set names 'gbk'");注释掉，肯定时乱码
screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onmousewheel="return imgzoom(this);" onclick="if(!this.resized) {return true;} else {window.open('/upload/20070902220748540.jpg');}" border=0 alt="" align=center src="http://files.glzy8.com/upload/20070902220748540.jpg" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}">
加上那句又正常了
screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onmousewheel="return imgzoom(this);" onclick="if(!this.resized) {return true;} else {window.open('/upload/20070902220748436.jpg');}" border=0 alt="" align=center src="http://files.glzy8.com/upload/20070902220748436.jpg" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}">
注意: set names 必须在连接数据库之后,执行sql语句之前!
一句话
你数据库用什么编码，在对数据库操作之前就set names '你的编码';
终于完了，如果对大家有用就顶下啦。不正确的地方也请指正