怪啦！今天的Apache和IIS都没法正确加载php_mysql.dll。google了一下，原来发现出现这个问题的人还不少，PHP startup: Unable to load dynamic library :E;\PHP5\ext\php_mysql.dll。明明php_mysql.dll就摆在extension_dir (= "E:/PHP5/ext")下的嘛，怎么会呢？而且就在php_mysql.dll之前的extension=php_gd2.dll都没有出现这个问题，怪了！有人说copy libmysql.dll到 ％windir％\system32下就可以解决问题，其实"华山不这一条道"：

PHP被我挪了个窝，%ProgramFiles%到E:\下，导致一些要依赖于其他dll才能工作的扩展无法正常加载这些dll，出现加载扩展出
错，以刚才的php_mysql.dll为例，php_mysql依赖libmysql.dll，由于给PHP5挪窝了，而又没有把新的E:\PHP5夹道%PATH%中去
，所以没法找到这个libmysql.dll，才会出错。所以为了能够使用这些mysql的扩展，除了要正确地配置extension_dir外
，还得保证系统能够这些扩展所依赖的dll，解决的办法有两个：
1 将这些依赖的dll拷贝到％windir％\system32下
2 或者将PHP5的安装目录添加到%PATH%中。
无论那个都可以很好地达到我们地目的。
够简单的，但是有时候还就想不到哪儿去。
到底哪些扩展依赖哪些dll呢？以下列表可以帮助我们回答这个问题：
php_curl.dll CURL, Client URL library functions Requires: libeay32.dll, ssleay32.dll (bundled)
php_domxml.dll DOM XML functions PHP <= 4.2.0 requires: libxml2.dll
(bundled) PHP >= 4.3.0 requires: iconv.dll (bundled)
php_fdf.dll FDF: Forms Data Format functions. Requires: fdftk.dll
gnu_gettext.dll (bundled), PHP >= 4.2.3 requires libintl-1.dll,
php_iconv.dll ICONV characterset conversion Requires: iconv-1.3.dll
php_ingres.dll Ingres II functions Requires: Ingres II libraries
php_interbase.dll InterBase functions Requires: gds32.dll (bundled)
php_java.dll Java functions PHP <= 4.0.6 requires: jvm.dll (bundled)
php_ldap.dll LDAP functions PHP <= 4.2.0 requires libsasl.dll(bundled),
PHP >= 4.3.0 requires libeay32.dll,ssleay32.dll (bundled)
php_mcrypt.dll Mcrypt Encryption functions Requires: libmcrypt.dll
php_mhash.dll Mhash functions PHP >= 4.3.0 requires: libmhash.dll (bundled)
php_mcrypt.dll Mcrypt Encryption functions Requires: libmcrypt.dll
php_mhash.dll Mhash functions PHP >= 4.3.0 requires: libmhash.dll (bundled)
php_msql.dll mSQL functions Requires: msql.dll (bundled)
php_mssql.dll MSSQL functions Requires: ntwdblib.dll (bundled)
php_mysql.dll MySQL functions PHP >= 5.0.0, requires libmysql.dll (bundled)
php_mysqli.dll MySQLi functions PHP >= 5.0.0, requires libmysqli.dll (bundled)
php_oci8.dll Oracle 8 functions Requires: Oracle 8.1+ client libraries
php_openssl.dll OpenSSL functions Requires: libeay32.dll (bundled)
php_oracle.dll Oracle functions Requires: Oracle 7 client libraries
php_sybase_ct.dll Sybase functions Requires: Sybase client libraries
php_xmlrpc.dll XML-RPC functions PHP >= 4.2.1 requires: iconv.dll (bundled)
php_xslt.dll XSLT functions PHP <= 4.2.0 requires sablot.dll, expat.dll (bundled).
PHP >= 4.2.1 requires sablot.dll, expat.dll, iconv.dll (bundled).