如何连接到本地MSSQL数据库

Question

EDIT: I've just tested it in ASP.NET and it works perfectly fine. So no issue with the connection string or anything. Guess Unity doesn't like this method? Maybe there's some more DLL's I need to copy? Any ideas?

So I'm making a game in Unity and I'm trying to use the System.Data.SqlClient library to connect to some stored procedures I have made for things such as registering a user.

I have copied the System.Data.dll from "C:\\Program Files\\Unity\\Editor\\Data\\Mono\\lib\\mono\\unity" and that has all worked fine.

I'm currently using this connection string, which works fine on an ASP.NET application but just using a different mdf:

private string connectionString = @"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename='C:\Users\uppy8\Desktop\Computer Science Project\Mining Game\Assets\MineRace.mdf';Integrated Security = True";

The problem occurs when running this code:

using System.Data.SqlClient;
using System.IO;

public void Login()
{
    Crypto crypto = new Crypto();

    using (SqlConnection conn = new SqlConnection(connectionString))
    {
        try
        {
            conn.Open();
        } catch (Exception e)
        {
            Debug.Log(e);
        }

        SqlCommand command = new SqlCommand("USERS_LOGIN_USER", conn);
        command.CommandType = CommandType.StoredProcedure;
        command.Parameters.Add(new SqlParameter("@Username", usernameInputField.text));

        using (SqlDataReader reader = command.ExecuteReader())
        {
            while (reader.Read())
            {
                if (crypto.EncryptString(passwordInputField.text) == reader["password"].ToString())
                {
                    UserAccountManager.instance.userInfo = FetchUserInfo((int)reader["id"]);
                }
            }
        }
    }

The problem happens on the line "conn.Open()", where Unity gives me the error:

System.Net.Sockets.SocketException: No such host is known.

Furthermore, without the try catch, the error occurs where I create a new SqlDataReader, where I get this issue:

InvalidOperationException: ExecuteReader requires an open connection to continue. This connection is closed.

I understand that this is an issue with the connection, in that it's not running or the connection isn't working properly, however I can't seem to find a solution and I have a sneaky suspicion that it's something to do with Unity not supporting this library.

Some more clarification just before I end off:

• The user enters their credentials into the "usernameInputField" and "passwordInputField"
• The user presses Login, which runs the "Login" method shown above
• The error occurs.

If any more information is required please leave a comment.

Thanks!

Answer 1

What is the scope of connectionString? Do you need to pass the connectionString to the Login() function?

public void Login(string connectionString)

I am a DBA, not a .Net developer, so forgive me if my questions are too basic or if my .Net syntax is wrong.

Answer 2

You can try this

string connectionString = @"Data Source = (localdb)\MSSQLLocalDB; Initial Catalog ='C:\USERS\uppy8\Desktop\Computer Science Project\Mining Game\Assets\MineRace.mdf'; Integrated Security = True; Connect Timeout = 30; Encrypt = False; TrustServerCertificate = True; ApplicationIntent = ReadWrite; MultiSubnetFailover = False"
        SqlConnection con = new SqlConnection();   
                    if (con.State==ConnectionState.Open)
                    {
                        con.Close();
                        con.ConnectionString = connectionString;
                        con.Open();
                        cmd.Connection = con;
                    }
                    else
                    {
                        con.ConnectionString = connectionString;
                        con.Open();
                        cmd.Connection = con;
                    }