This article demonstrates how to use an OLE DB Universal
Data Link (.udl) file to specify the connection string that an ADO.NET OleDbConnection
object uses to establish a database connection.
Universal Data Link (.udl) files provide a convenient way to create and verify
an ActiveX Data Objects (ADO) connection string that is used to connect to an
OLE DB data source. The connection string information is persisted in a
specific format to a file with the .udl extension.
You can reference
a .udl file in the ConnectionString
property of an ADO.NET OleDbConnection
object to specify the connection string that the object should
use to connect to a database. Use the File Name
parameter of the connection string to specify the name of the
.udl file that contains the connection string information.
Steps to build the sample
Follow these steps to create a Visual Basic .NET Console
Application that uses a .udl file to specify the connection string information
for an ADO.NET OleDbConnection
- Use the SQL Server OLE DB Provider to connect to one of
your Microsoft SQL Server databases, and create a .udl file named Test.udl in
the root folder of drive C. You can also use the Microsoft OLE DB Provider for
Jet 4.0 to configure the .udl file to connect to a Microsoft Access 97 or 2000
database if you do not have access to a SQL Server database.
For more information about how to create a .udl file, click the following article number to view the article in the Microsoft Knowledge Base:
189680NOTE: When you create the .udl file, make sure to select the Allow Saving Password option on the Connection tab.
How to use Data Link files with ADO
- Test the connection from the .udl file.
- Open a new Visual Basic .NET Console Application.
- Replace the default code in the Module1 code module with the following code:
Imports Console = System.Console
Dim response As String
Dim cn As New OleDbConnection()
cn.ConnectionString = "File Name=c:\test.udl"
If cn.State = ConnectionState.Open Then
Console.WriteLine("Connection opened successfully")
Console.WriteLine("Connection could not be established")
cn = Nothing
response = Console.ReadLine()
- In the statement that sets the ConnectionString property of the OleDbConnection object, modify the path to the .udl file if you created it with a
different name or persisted it to a different location.
- Run the application from within the Visual Studio .NET
Integrated Development Environment (IDE). A console window should open and
display the text, "Connection opened successfully!" to indicate that the OleDbConnection object was able to use the connection string information in the
.udl file to establish the database connection.
- Press any key to dismiss the console window and stop the
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
How to create a Data Link file with Windows 2000
Article ID: 308075 - Last Review: December 28, 2005 - Revision: 3.1
- Microsoft ADO.NET (included with the .NET Framework)
- Microsoft ADO.NET 1.1
- Microsoft Visual Basic .NET 2002 Standard Edition
- Microsoft Visual Basic .NET 2003 Standard Edition
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