Create Database Link from One Server to Another in Oracle

Establishing a database link between two servers is a crucial aspect of database management in Oracle. This process allows for seamless data exchange and query execution across different databases. In this article, I will guide you through the steps to create a database link from one server to another, providing you with a comprehensive understanding of the process.

Understanding Database Links

A database link in Oracle is a logical pointer that enables access to remote databases. It allows users to connect to a remote database as if it were a local database. This feature is particularly useful in scenarios where data needs to be shared or queried across multiple databases.

Prerequisites for Creating a Database Link

Before creating a database link, ensure that the following prerequisites are met:

• Both the source and target databases must be running.
• The user creating the database link must have the necessary privileges.
• The network connection between the source and target servers must be established.

Creating a Database Link

Follow these steps to create a database link from one server to another:

1. Log in to the source database as a user with the necessary privileges.
2. Use the following SQL statement to create the database link:

CREATE DATABASE LINK   CONNECT TO   IDENTIFIED BY   USING '';

Replace with the desired name for the database link, with the username to connect to the target database, with the password for the username, and with the service name of the target database.

Example

Suppose you want to create a database link named “sales_link” from the source database “source_db” to the target database “target_db” on the server “target_server”. The username for the target database is “target_user” with the password “target_password”, and the service name is “target_service”. The SQL statement would be:

CREATE DATABASE LINK sales_link  CONNECT TO target_user  IDENTIFIED BY target_password  USING 'target_service';

Verifying the Database Link

After creating the database link, verify its existence using the following SQL statement:

SELECT  FROM all_db_links WHERE link_name = 'sales_link';

This statement will return the details of the database link, including its name, username, password, and service name.

Using the Database Link

Once the database link is created and verified, you can use it to access the target database. To query data from the target database, use the following syntax:

SELECT  FROM @;

Replace with the name of the table in the target database, and with the name of the database link.

Conclusion

Creating a database link from one server to another in Oracle is a straightforward process. By following the steps outlined in this article, you can establish a secure and efficient connection between two databases, enabling seamless data exchange and query execution.