You will discover how to use and manage connection strings in the program in this post.

The following queries will be addressed:

• A Connection String: What Is It?
• How many ways exist for connection strings to be defined and managed?
• Examples of Codes

What is a Connection String?
The connection string is one kind of text string that is used to establish a connection from the application to the database server database. The connection string is the collective information of the data source, database name, user name, and password.

How many ways to define and manage connection strings?
Following ways to declare and manage the connection strings:

• AppSettings.json
• Environment Settings
• Static Class

AppSettings.json
Using the AppSettings.json file, you can easily write a connection string.

Define Connection-String
Creating a separate object under the main json object just below Logging.
{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "ConnectionStrings": {
    "MyConnectionString": "Server=xxx.xx.xxx.xx;Database=dbTest;User=xxxxxxx;Password=xx@xx;TrustServerCertificate=True"
  },
  "AllowedHosts": "*"
}

Using Connection-String
Open the HomeController.cs file and update the code.
public class HomeController : Controller
{
    // Inject the IConfiguration interface into your controller to access the connection string from appsettings.json file
    private readonly IConfiguration _configuration;
    private readonly ILogger<HomeController> _logger;

    public HomeController(ILogger<HomeController> logger, IConfiguration configuration)
    {
        _logger = logger;
        _configuration = configuration;
    }

    public IActionResult Index()
    {
        // Get the connection string
        string connectionString = _configuration.GetConnectionString("MyConnectionString");
        return View();
    }

    public IActionResult Privacy()
    {
        return View();
    }

    [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
    public IActionResult Error()
    {
        return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
    }
}

Environment Settings
Using the environment setting, it takes more steps to configure the connection string than the appsettings.json file.
Note. You can set environment variables in two ways.

Command Window
setx MyDbConnect "Server=(localdb)\\MSSQLLocalDB;Database=dbMyDb;Trusted_Connection=Tr

Edit Environment Variable Dialog box.

Search for “environment” in the start menu.
You can add the new environment variable by clicking the NEW button.

You can check and update the connection string in Local environment variables

To fetch the local environment variables
string Connt = Environment.GetEnvironmentVariable("MyDbConnect");

Note. You may get null value from above line, you have to restart the Visual Studio because visual studio read Environment Variable at startup only.

Static Class
Create a static class and static property to set the connection string.
public static class DbConnect
{
    public static string DbConnectionString { get; set; } =
        "Server=xxx.xx.xxx.xx;Database=dbTest;User=xxxxxxx;Password=xx@xx;TrustServerCertificate=True";
}

You can use it in the following way:
string ConStr = DbConnect.DbConnectionString;

Happy Coding.