How to: Save a Connection String
Connection strings in Visual Studio applications can be saved in the application configuration file (also referred to as application settings), or hard-coded directly in your application. Saving connection strings in the application configuration file simplifies the task of maintaining your application. If the connection string needs to be changed, then you can update it in the application settings file (as opposed to having to change it in the source code and recompile the application).
Storing sensitive information (such as the password) within the connection string can affect the security of your application. Connection strings saved to the application configuration file are not encrypted or obfuscated, so it may be possible for someone to access the file and view its contents. Using Windows Integrated Security is a more secure way to control access to a database.
If you do not choose to use Windows integrated security and your database requires a user name and password, you can omit them from the connection string, but your application will need to provide this information to successfully connect to the database. For example, you can create a dialog box that prompts the user for this information and dynamically builds the connection string at run time. Security can still be an issue if the information is intercepted on the way to the database.
For more information, see Protecting Connection Information (ADO.NET).
To save a connection string from within the data wizards
Select the option to save the connection on the Save connection string to the application configuration file page.
To view or edit the connection string, see How to: Edit a Connection String.
To save a connection string directly into application settings
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.
Type your connection string into the Value field.
Click the ellipses (...) button in the Value field to open the Connection Properties dialog box to build your connection string. For more information, see Add/Modify Connection Dialog Box (General).
Storing sensitive information (such as a password) within the connection string can affect the security of your application. Using Windows integrated security is a more secure way to control access to a database.