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Connecting VS2010 to Oracle driver: Resolving ORA-12154 TSN connection identifier

Introduction: Visual Studio 2010 (VS2010) is a powerful integrated development environment (IDE) used by many developers for creating applic...


Visual Studio 2010 (VS2010) is a powerful integrated development environment (IDE) used by many developers for creating applications. One of the key features of VS2010 is its ability to connect to various databases, including Oracle. However, when trying to establish a connection to an Oracle database using VS2010, the user might encounter an error message that reads: "ORA-12154 TSN: could not resolve the connect identifier specified." This article will guide you through the steps to resolve this error and successfully connect VS2010 to the Oracle driver.

Step 1: Install the Oracle Driver

The first step to connecting VS2010 to an Oracle database is to install the Oracle driver. This driver is required for VS2010 to communicate with the Oracle database. You can download the driver from the official Oracle website or use the installation CD that came with your Oracle database.

Step 2: Configure the TNS Names File

The TNS names file is a configuration file used by Oracle to store connection information for databases. This file is essential for establishing a connection between VS2010 and the Oracle database. To configure the TNS names file, follow these steps:

1. Open the Oracle installation directory and locate the "network" folder.

2. Inside the "network" folder, you will find a file named "tnsnames.ora." Open this file using a text editor.

3. Add a new entry for your Oracle database in the following format:

<database name> =



(ADDRESS = (PROTOCOL = TCP)(HOST = <hostname or IP address>)(PORT = <port number>))



(SERVICE_NAME = <service name>)



4. Save the changes to the tnsnames.ora file and exit the text editor.

Step 3: Configure the Environment Variables

To establish a connection to the Oracle database, VS2010 needs to know the location of the TNS names file. This information is stored in the TNS_ADMIN environment variable. To configure this variable, follow these steps:

1. Right-click on "My Computer" and select "Properties."

2. Select the "Advanced" tab and click on "Environment Variables."

3. Under the "System Variables" section, click on "New."

4. In the "Variable Name" field, enter "TNS_ADMIN."

5. In the "Variable Value" field, enter the path to your "network" folder where the tnsnames.ora file is located.

6. Click "OK" to save the changes.

Step 4: Test the Connection

Now that the necessary configurations are in place, it's time to test the connection. Follow these steps:

1. Open VS2010 and create a new project.

2. Right-click on "References" and select "Add Reference."

3. In the "Add Reference" window, select the "Browse" tab and navigate to the "Oracle.DataAccess.dll" file located in the Oracle installation directory.

4. Click "OK" to add the reference.

5. Write the code to establish a connection to the Oracle database.

6. Run the code, and if the connection is successful, you will see a message confirming the connection.


In this article, we have discussed the steps to connect VS2010 to an Oracle database and resolve the ORA-12154 TSN connection identifier error. By following these steps, you can establish a successful connection and start developing applications using VS2010 and Oracle. With the right configurations and proper understanding, connecting to databases through VS2010 becomes a seamless process.

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