学习php编程遇到 

Uncaught exception ‘PDOException‘ with message ‘could not find driver‘

或者 

Undefined class constant ‘MYSQL_ATTR_INIT_COMMAND‘

整两个问题,网上找了很多资料,很多是这样解决的

配置php.ini文件添加extension=php_pdo_mysql.dll，，这样就开启pdomysql扩展库 

但是我没有解决问题,问题还是老样子,后来在stackoverflow 找到了问题地址

具体链接

问题出在了

extension_dir = "ext"

改成绝对路径就可以了

; Directory in which the loadable extensions (modules) reside. ; ; extension_dir = "./" ; On windows: extension_dir = "D:/php-5.4.11-Win32-VC9-x86/ext"

原因

in php.ini and php -m was starting fine and reporting that it loaded pdo_mysql, but when I ran phpinfo.php through apache, the driver was missing.

I fixed it by changing the extension_dir to an absolute path. I‘m guessing it got confused when running through Apache and made it relative to something else.　　

我固定它通过转变extension_dir绝对路径。我猜它混淆了运行时通过Apache和相对付另外对象。

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