Save and edit database connection strings for .NET Framework applications
Note
Datasets and related classes are legacy .NET Framework technologies from the early 2000s that enable applications to work with data in memory while the applications are disconnected from the database. The technologies are especially useful for applications that enable users to modify data and persist the changes back to the database. Although datasets have proven to be a very successful technology, we recommend that new .NET applications use Entity Framework Core. Entity Framework provides a more natural way to work with tabular data as object models, and it has a simpler programming interface.
This article provides guidance for handling database connection strings in Windows applications. However, for cloud and web applications, more secure techniques are available. You can use Connected Services to add support for the secrets.json file for local development, and then migrate to Azure Key Vault for secrets storage when you deploy to Azure. For more information, see Protect secrets during development.
Security considerations
To avoid security risks, it's important to properly handle the connection string in a Visual Studio application. Connection strings in Visual Studio applications are often saved in the application configuration file (also referred to as application settings), or hard-coded directly in your application. Hard-coding directly into the application isn't recommended, because the sensitive information in the connection string, such as the database credentials, can be read directly from the unencrypted binaries. It's more secure to save your connection strings in the application configuration file, which also simplifies the task of maintaining your application. If the connection string needs to be changed, you can update it in the application settings file, instead of changing it in the source code and recompiling the application.
If you store sensitive information, such as a password, within the connection string it can affect the security of your application. Because connection strings saved to the application configuration file aren't encrypted, it might be possible for someone to access the file and view its contents. If your database requires a user name and password, you can omit them from the connection string. However, your application must somehow provide this information to successfully connect to the database. For example, if you create a dialog box that prompts a user for a name and password and dynamically builds a connection string at run time, this information might be intercepted on the way to the database.
To avoid these security issues, for databases that support it, use Windows integrated security for a more secure way to control access to a database. For more information, see Protect connection information.
Save database connection strings
You can save a database connection string in application settings or in a dataset.
Save a connection string in application settings
To save a connection string directly in application settings, follow these steps:
In Solution Explorer, do one of the following steps, depending on your project type:
- For a C# project, expand the project and double-click the Properties node.
- For a Visual Basic project, expand the project and double-click the My Project node.
The Project Designer opens.
Select the Settings tab.
Enter a Name for the connection string. Refer to this name when accessing the connection string in code.
Set the Type to (Connection string).
Leave the Scope set to Application.
Enter your connection string in the Value field, or select the ellipsis (...) button in the Value field to open the Connection Properties dialog box to build your connection string.
Save a connection string in a dataset
To save a connection string in a dataset by using the Data Source Configuration Wizard, follow these steps:
On the Choose Your Data Connection page, select a data connection and choose Next.
On the Save the Connection String to the Application Configuration File page, select the option to save the connection to the application configuration file.
Edit database connection strings
You can edit an existing database connection string in application settings or in a dataset.
Edit a connection string in application settings
To edit a connection string in application settings:
In Solution Explorer, do one of the following steps, depending on your project type:
- For a C# project, expand the project and double-click the Properties node.
- For a Visual Basic project, expand the project and double-click the My Project node.
The Project Designer opens.
Select the Settings tab.
Locate the connection you want to edit and select the text in its Value field.
Edit the connection string in the Value field, or select the ellipsis (...) button in the Value field to edit your connection with the Connection Properties dialog box.
Edit a connection string in a dataset
You can modify connection information for a TableAdapter or query in a dataset.
To edit a connection string in a dataset, follow these steps:
In Solution Explorer, double-click the dataset (.xsd file) that has the connection you want to edit.
Select the TableAdapter or query that has the connection you want to edit.
In the Properties window, expand the Connection node.
To modify the connection string, edit the ConnectionString property, or select the down arrow on the Connection node and choose New Connection.