Error - "The server was not found or was not accessible" when trying to connect to sql server database

Question

I'm working on a local project and trying to connect to a local database. I have this class in it the connection string:

public class SQLConnection
{
    public static string connectionString =
        @"Data Source=TZVIKA-PC\SQLEXPRESS;Initial Catalog=WorldCup;Integrated Security=True";

    public static WorldCupDBDataContext wcDataContext = 
        new WorldCupDBDataContext(connectionString);

    public static WorldCupDBDataContext GetDataContextInstance()
    {
        return wcDataContext;
    }
}

when I try to execute this line in a windows form:

 teamBindingSource.DataSource = database.Teams.OrderBy(team => team.TeamId);

I get the following sql exception:

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)

My friend ran the code and it works on his pc(when changing the connection string of course to a relevant one)

Why is it not working for me?

Answer 1

A good (and easy) way to test if your SQL connection is working is to use a .UDL file. Simply create an empty text (.txt) file on your desktop and rename the extension to .udl. Double click and you'll be presented with a SQL connection window, fill in the details, test connection and then (when it's working) save. Close the window and rename the file extension to .txt. Open and inside you'll find your working connection string.