在PLSQL Developer选择Tools > Preferences > options > 下的如图所示："Oracle Home" and "OCI Library"

Oracle10g装在d:/oracle/ Oracle Home为d:/oracle/product/10.1.0

OCI Library为d:/oracle/product/10.1.0/Db_1/BIN/oci.dll

配置完以后重新启动PLSQL Developer，登录成功

配置过后登陆时仍然报错：

Could not load "……/bin/oci.dll"

OCIDLL forced to……

LoadLibrary(……oci.dll) returned 0

解决办法是：在64位的机器上安装32位的Oracle客户端。这样的话便连接成功。

依据：

从安装角度考虑，32bit的平台(操作系统和硬件系统)只支持32bitORACLE的安装；

64bit平台既支持32bitORACLE的安装也支持64位ORACLE的安装；

根据PL/SQL Developer的官方论坛里面的帖子：

quote:

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

I am not too fond of installing both 32 and 64 bit oracle clients on same machine - does it work at all?

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

Yes, this works fine. --这是管理员的回复

PL/SQL Developer is written in Delphi.

The first thing that needs to become available is a 64 bit version of the Delphi IDE.

还有另外一个帖子也提到：

Hi when install in Windows Server 2003 R2 X64.

When I try to connect an account , I have the following message :

Initialization error

Could not load"E:/oracle/product/10.2.0/bin/oci.dll"

--以下是管理员的回复

Is this a 64 bit Oracle Client DLL?

If so, please note that you need to install a 32 bit Oracle Client to use a 32 bit application like PL/SQL Developer.

呼，终于解决了，在客户的web机上无法用PL/SQL连到linux上的Oracle数据库

原文：http://www.cnblogs.com/WtJavaSkill/p/4786819.html