I believe that this is happens especially with Windows 7. As far I I've been able to tell XP and Vista come with this line enabled, but windows 7 comments it out and notes that the DNS will handle this.
安装
警告
本扩展自 PHP 5.5.0 起已废弃，并在自 PHP 7.0.0 开始被移除。应使用 MySQLi 或 PDO_MySQL 扩展来替换之。参见 MySQL：选择 API 指南来获取更多信息。用以替代本函数的有：
编译时，只要使用
--with-mysql[=DIR]
配置选项即可，其中可选的
[DIR] 指向 MySQL 的安装目录。
虽然本 MySQL 扩展库兼容 MySQL 4.1.0 及其以后版本，但是它不支持这些版本提供的额外功能。要使用这些功能，请使用 MySQLi 扩展库。
如果要同时安装 mysql 扩展库和 mysqli 扩展库，必须使用同一个客户端库以避免任何冲突。
在 Linux 系统下安装
Note: [DIR] is the path to the MySQL client library
files (headers and libraries), which can be downloaded from
» MySQL.
| PHP 版本 | 默认 | 配置选项: mysqlnd | 配置选项: libmysql |
更新日志 |
|---|---|---|---|---|
| 4.x.x | libmysql | 不适用 | --without-mysql to disable | MySQL enabled by default, MySQL client libraries are bundled |
| 5.0.x, 5.1.x, 5.2.x | libmysql | 不适用 | --with-mysql=[DIR] | MySQL is no longer enabled by default, and the MySQL client libraries are no longer bundled |
| 5.3.x | libmysql | --with-mysql=mysqlnd | --with-mysql=[DIR] | mysqlnd is now available |
| 5.4.x | mysqlnd | --with-mysql | --with-mysql=[DIR] | mysqlnd is now the default |
在 Windows 系统下安装
PHP 5+
MySQL 默认未启用，因此必须在 php.ini 中激活 php_mysql.dll 动态连接库。此外，PHP 还需要访问 MySQL 客户端连接库。PHP 的 Windows 发行版包括了一个 libmysql.dll，为了让 PHP 能和 MySQL 对话，此文件必须放在 Windows 的系统路径 PATH 中。怎样做见 FAQ 中的“怎样把 PHP 目录加入到 Windows PATH中”。尽管将 libmysql.dll 拷贝到 Windows 系统目录中也可以（因为系统目录默认在系统路径 PATH 中），但不推荐这样做。
要激活任何 PHP 扩展库（例如
php_mysql.dll），PHP 指令
extension_dir
要被设为 PHP 扩展库所在的目录。参见手工 Windows
安装指南。PHP 5 下 extension_dir 取值的一个例子是
c:\php\ext。
注意:
如果启动 web 服务器时出现类似如下的错误：
"Unable to load dynamic library './php_mysql.dll'"，这是因为系统找不到 php_mysql.dll 和／或 libmysql.dll。
PHP 5.3.0+
The MySQL Native Driver is enabled by default. Include php_mysql.dll, but libmysql.dll is no longer required or used.
MySQL 安装注意事项
警告
当同时加在本扩展库和 recode 扩展库时 PHP 可能会崩溃。更多信息见 recode 扩展库。
注意:
如果需要不同于 latin（默认值）的字符集，必须安装外部的（非绑定的）已编译入所需字符集支持的 libmysql。
add a note
User Contributed Notes 7 notes
heneryville at gmail dot com ¶
14 years ago
jonnus ¶
16 years ago
In windows systems, the same error "unable to load dynamic library php_mysql.dll" will happen, if there's an old version of the file in the "windows\system32" folder.
Either remove it or update it.
buzzr515 at gmx dot de ¶
14 years ago
i've experienced a similar (if not the same) problem.
to enable the mysql_... and mysqli_... funtionality, i opened the php.ini file to uncomment the following lines:
;extension=php_mysql.dll
;extension=php_mysqli.dll
;extension=php_pdo_mysql.dll
but phpinfo() still stated that no mysql extensions were loaded.
i tried the fixes and suggestions above with no success.
so i invoked the windows shell and typed ("Path" environment variable set to the PHP & MySQL directories):
php.exe -m
this returned the following error: "PHP Startup: Unable to load dynamic library 'C:\php5\php_mysql.dll' - Module not found."
this told me that PHP didn't recognize what i thought was the extensions directory. it searched all other places first (sys-dir, workin'-dir, the MySQL "bin" dir because of the "Path" variable set, and even a curious directory "C:\php5" that doesn't even exist on my mashine) but not the expected "ext" directory.
so the fix was to go to "php.ini" again and uncomment the following line:
;extension_dir="ext"
this fixed it for me.
so if module loading is done improperly, first of all check the "Path" environment variable and the "php.ini" file - especially the "extension_dir" config value - and check if all values are set to their correct values.
hope this helps any1.
----------------------------------------
OS: Win7 Ultimate x86
Apache v2.2.16
PHP v5.3.3
MySQL v5.1.50
mail dot umlcat at gee mail dot com ¶
12 years ago
Could not install mysql, on windows, had several conflicts or bugs.
In order to solve it:
* Used the "libmysql.dll" provided by PHP zip files, not the one that comes with Mysql, the mysql file had to be moved or deleted from its folder. Put it on the "apache/bin" folder, altought some use it in "windows" folder.
* Originally, moved "*mysql*.dll" files from its extension folder, and returned back.
* enabled mysql driver extensions in the "php.ini" file, but also enabled some extensions, that seemed not to be required, but, it did, like "php_openssl.dll" or "php_pdo.dll" on an early version of php.
Added the "PHPIniDir xxx"" to the "httpd.conf" apache config. file, where xxx is the path to the folder where the "php.ini" file is located, and make sure its the same.
Be warned, that this fixes, may help or not, for your installation, since there are many ways to configure the same thing (to solve a problem).
Steve in Weston-Super-Mare ¶
13 years ago
I had problems when moving from a version of PHP that used the isapi dll to the fast cgi version. The script to register the script maps compained that there was already a script map in place.
I went to the IIS control panel, right clicked on websites and removed the php association in the Home Directory | Configuration screen.
However, the fastcgi script still complained about existing script map. Finally I tracked it down, I had to right click on Default Web Site and clear out the php mappings from there too.
Then it all worked, except that for some strange reason, the php.ini file that gets picked up is the one from my old PHP directory, not the latest upgrade one. But this can be detected by running phpinfo which shows the loaded php.ini file so I knew which one to amend with the fastcgi options.
Bit of a hassle to figure it all out but it does work in the end.
amatsak at gmail dot com ¶
15 years ago
I have experienced exactly the same problem as flo_stefi at yahoo dot com below. It appears that instead of loading libmysql.dll that came with the PHP package, the PHP engine was loading libmySQL.dll located in MySQL's bin directory, which was causing Apache to crash.
I fixed the problem by renaming MySQL's libmySQL.dll into libmySQL_renamed.dll. Now PHP loads the library that came with its package and everything works fine.
o dot kochetilov at gmail dot com ¶
13 years ago
Please note that libmySQL.dll in MySQL bin directory should be renamed in order to use right library (that comes with PHP).
