1.首先下载两个程序包：
Instant Client Package - Basic（或Instant Client Package - Basic Lite）包
Instant Client Package - SQL*Plus包
下载地址：
http://www.oracle.com/technology/global/cn/software/tech/oci/instantclient/index.html
2.将Instant Client Package – Basic和Instant Client Package - SQL*Plus解压，
例将其中的文件放在目录C:Instantclient10_2下
3.设置环境变量：
1)在环境变量PATH中开头增加C:Instantclient10_2;
2)增加用户环境变量SQLPATH，值为C:Instantclient10_2
3)增加用户环境变量NLS_LANG，值为AMERICAN_AMERICA.UTF8（中文可能乱码，可改用AMERICAN_AMERICA.ZHS16GBK）
4.到此已经可以用SQL*Plus连接远程数据库，但书写方式必须如下例：
Sqlplus SYS/SYS@//192.168.0.2:1521/VMORCL
如果想要使用配置于TNSnames.ora中的连接字符串来连接，
增加环境变量TNS_ADMIN，
值为tnsnames.ora所在的目录，例： C:Instantclient10_2 etworkadmin(建立
C:Instantclient10_2 etworkadmin目录，将TNSnames.ora放在此目录下)，
并编辑TNSnames.ora
如：
LORCL=
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS =
(PROTOCOL = TCP)
(Host = 192.168.159.128)
(Port = 1521)
)
)
(CONNECT_DATA = (SID = LORCL)
)
)
此时连接数据库，例：
Sqlplus sys/sys@vmorcl as sysdba
或sqlplus sys@vmorcl as sysdba
另：使用PL/SQL Developer的话，直接在preference中将oracle home 设置为C:instantclient10_2,oci library
设为C:instantclientoci.dll
------------------------------------------------------------设置结束----------------------------------------------------------------
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附：
一个网友按照上面步骤做了之后说还是不可以用，报错，
Initialization error
Could not load “C:Instantclient10_2oci.dll”
OCIDLL forced to C:Instantclient10_2oci.dll
LoadLibrary(C:Instantclient10_2oci.dll) returned 0
折腾很久没找到原因，后来他告诉我说他的目录不是C:Instantclient10_2，而是C:Instantclient11_XX，无语..
把自己Developer的Oracle Home的目录改成一个不存在的目录，测试，果然出现他所说的错误，如下
而且登陆框是下面这个样子
明显没有应用到那个InstantClient中的组件…
正常的时候应该像如下：
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附：SQL*Plus? User's Guide and Reference Release 10.2中详细说明
http://download.oracle.com/docs/cd/B19306_01/server.102/b14357/ape.htm#sthref3926
Oracle Call Interface Programmer's Guide for more information on the OCI Instant Client.
To Oracle Database Globalization Support Guide, and NLS_LANG Environment Variable for more information about NLS settings.
http://www.oracle.com/technology/tech/oci/instantclient/instantclient.html
. Both packages must be from the same version such as 10.2.0.1.
2. Use rpm -i for the initial install of the RPM packages, or rpm -u to upgrade to a newer version of the packages.
3. Configure SQL*Plus Instant Client. See Configuring SQL*Plus Instant Client.
http://www.oracle.com/technology/tech/oci/instantclient/instantclient.html
. Both packages must be from the same version such as 10.2.0.1.
2. Create a new directory, for example, /home/instantclient10_2 on UNIX or c:instantclient10_2 on Windows.
3. Unzip the two packages into the new directory.
4. Configure SQL*Plus Instant Client. See Configuring SQL*Plus Instant Client.
Installing SQL*Plus Instant Client on UNIX or Linux or Installing SQL*Plus Instant Client on Windows for a list of the files to copy.
4. Configure SQL*Plus Instant Client. See Configuring SQL*Plus Instant Client.
Oracle Database Globalization Support Guide for more information.
For example:
NLS_LANG=AMERICAN_AMERICA.UTF8
export NLS_LANG
Oracle Database Globalization Support Guide for more information.
For example:
NLS_LANG=AMERICAN_AMERICA.UTF8
export NLS_LANG
Oracle Database Globalization Support Guide for more information. For example, to set NLS_LANG for a Japanese environment, create a user environment variable NLS_LANG set to JAPANESE_JAPAN.JA16EUC.
If you have installed the lightweight Instant Client, see Lightweight Instant Client for information about supported NLS_LANG settings.
Oracle Database Net Services Reference for more information.
If you want to use Net Service Names configured in a local Oracle Net tnsnames.ora file, then set the environment variable TNS_ADMIN to the directory containing the tnsnames.ora file. For example, on UNIX, if your tnsnames.ora file is in /home/user1 and it defines the Net Service Name MYDB2:
TNS_ADMIN=/home/user1
export TNS_ADMIN
sqlplus hr@MYDB2
If TNS_ADMIN is not set, then an operating system dependent set of directories is examined to find tnsnames.ora. This search path includes looking in the directory specified by the ORACLE_HOME environment variable for network/admin/tnsnames.ora. This is the only reason to set the ORACLE_HOME environment variable for SQL*Plus Instant Client. If ORACLE_HOME is set when running Instant Client applications, it must be set to a directory that exists.
This example assumes the ORACLE_HOME environment variable is set, and the $ORACLE_HOME/network/admin/tnsnames.ora or %ORACLE_HOME% etworkadmin nsnames.ora file defines the Net Service Name MYDB3:
sqlplus hr@MYDB3
The TWO_TASK (on UNIX) or LOCAL (on Windows) environment variable can be set to a connection identifier. This removes the need to explicitly enter the connection identifier whenever a connection is made in SQL*Plus or SQL*Plus Instant Client. This UNIX example connects to the database known as MYDB4:
TNS_ADMIN=/home/user1
export TNS_ADMIN
TWO_TASK=MYDB4
export TWO_TASK
sqlplus hr
On Windows, TNS_ADMIN and LOCAL may be set in the System Properties. SeeConfiguring SQL*Plus Instant Client on Windows.
Oracle Database Administrator's Guide for information on Oracle password files.
Installing SQL*Plus Instant Client from the 10g Client Release Media for a list of the files you copied to the directory.
2. Reset environment variables such as PATH, SQLPATH, LD_LIBRARY_PATH and TNS_ADMIN.
3. Remove tnsnames.ora if necessary.