SQL database developer tip: quickly test your ADO.NET connection strings without any tools or code

Sometimes, you need to diagnose SQL database connection issues you're having in your .NET applications using either Entity Framework and/or ADO.NET within the customer site. When this happens, you usually don't have the convenience of your developer tools: Visual Studio's Server Explorer, or SQL Server Management Studio (SSMS).

But, here's a nice little trick: use so-called UDL files, an old Windows feature. These are officially called Universal Data Link (UDL) files.

Here are quick instructions:

1. Create an empty file, such as “test.udl” in any folder, such as the computer desktop. You can first create a new text file, and the change the file extension.
2. Open the file by double-clicking it.
3. A familiar connection string editor opens. Now enter the required details.
4. Test the connection to see if it works. Once you are done, save the settings by clicking OK.
5. Open the file with a text editor, such as Notepad, and take note of the generated connection string.

Good luck in solving your database connectivity issues!