How to Connect Oracle Client to Oracle Server........!

Procedure

1. Start Oracle Net Configuration Assistant.
2. On the Welcome page, select Local Net Service Name configuration and click Next.
3. On the Net Service Name Configuration page, select Add and click Next.
4. On the Net Service Name Configuration, Service Name page, type RICM and click Next.
5. On the Net Service Name Configuration, Select Protocols page, select TCP and click Next.
6. On the Net Service Name Configuration, TCP/IP Protocol page, enter the host name and use default port number 1521 unless it has changed. Click Next.
7. On the Net Service Name Configuration, Test page, select Yes, perform a test and click Next.
8. For the first test, if the connection fails, click Change Login, and provide the new user name and password. Then, repeat the test. After the test connects successfully, click Next.
9. On the Net Service Name Configuration, Another Net Service Name page, select No and click Next.
10. On the Net Service Name Configuration Done page, click Next.
11. Close Net Configuration Assistant.

Open Oracle Net Configuration

1. Start Oracle Net Manager by clicking the Start button and then selecting Programs, Oracle, Configuration and Migration Tools, and Net Manager. 
2. From the Local tree, select Service Naming and click the plus (+) on the left hand side of the page.The Net Service Name Wizard appears.
   
   
3.  Enter a net service name to identify it. The name you choose will appear under the Service Naming folder. Click Next.
4. Select the protocol to use to connect to your database. For example, you can accept the default of TCP/IP (Internet Protocol). The database listener must be configured to use the same network protocol. Click Next.
5. Host Name. Enter the IP address(like as:-10.7.1.157) or host name of the machine on which the Oracle server resides. Use localhost if the database resides on your own machine.
6. Port Number. The default port (1521) will generally be the correct value. However it is possible that your DBA has configured Oracle to use a different port; check with him/her. 
7. The last screen of the wizard enables you to test the connection by using the information you entered. To do so, click Test. To log in to the database, you can use the SYS user and the password you specified when you configured your database. The wizard tells you if the connection test succeed or not.
   
8. Click Finish. The new service appears under the Service Naming folder. You can view or modify the configuration for the highlighted service in the Service Identification and Address Configuration sections.
   

 Now Open Oracle on your System (SQL Plus) Give the username,password and HostString(Listener Name) And Press Enter.

How To Remove Oracle Services:-


Go to Registry.
Take a backup of Registry.
should go to registry HKEY_LOCAL_MACHINE
then go to
system
then go to
current control set
then go to
services
there you remove oracle services.