Why can't I connect to the SQL Server database when I create setup file in Visual studio?

Question

I create application using C# windows forms which uses local SQL Server database server to store / read data using this connection string:

 SqlConnection cn = new SqlConnection("Data Source=localhost;Initial Catalog=mydb;Integrated Security=True");

After that I created a setup file (exe) then I installed the setup file in same PC and the application works well and can read data from the SQL Server database.

Now the problem came when I went to another PC I installed SQL Server and I manually attached the same database (mydb) and installed my application and it did not work. The error is shown in the screenshot:

I have different SQL Server name in the other PC but I specified in the connection string that the SQL Server is Localhost so I don't know why it didn't work. Please help me how to fix this error. Thank you

Answer 1

Make sure Sql Server is set to allow Tcp/Ip connections and that it's set to allow integrated security logins. Then, make sure the user on that machine is granted the correct access to the database. You may have better luck using Sql authentication over Windows Authentication here, if you want to be able to distribute this application and have it "just work".

Finally, if Sql Server here is meant to be a simple datastore for a typical local desktop application, it's probably overkill. Full Sql Server (including Express Edition) is a server engine. It works best when it's the only thing running on the machine and can use up all of the resources on the machine in order to cache data and handle requests from many remote machines. If you just want a local data store for a typical desktop application, an in-process engine like Sql Server LocalDb, Sql Server Compact Edition, Sqlite, or even MS Access would be a much more appropriate choice.

Answer 2

You need to set up Windows authentication for the user that's logged in on the other computer. Because you are using Integrated Security, it will attempt to connect to SQL Server using the windows login of the current user. This will be a different login on different computers, so the SQL Server on the other computer needs to have that user added.

Answer 3

You need to start SQL Server Browser Service . It lets your app connects to SQL Server:

SQL Server Browser listens for incoming requests for Microsoft SQL Server resources and provides information about SQL Server instances installed on the computer.

To enable it:

In SQL Server Configuration Manager, go to Properties => Service tab => Start Mode = Automatic.

Or

This computer => Manage => Services and Applications => Services => SQL Server Broswer

Note: You need a sql specific user for connect to it, you can not go with Integrated Security for every machine.

Create a Sql Server user and allow it to access the Database:

--//Creates the login AbolrousHazem with password '340$Uuxwp7Mcxo7Khy'.
CREATE LOGIN AbolrousHazem 
    WITH PASSWORD = '340$Uuxwp7Mcxo7Khy';
GO

--//Creates a database user for the login created above.
CREATE USER AbolrousHazem FOR LOGIN AbolrousHazem;
GO

Reference