validateLogin() public method

Used to validate the login of a user
public validateLogin ( string username, string password ) : int
username string Username
password string Password
return int
        private void submitButton_Click(object sender, EventArgs e)
        {
            MessageLabel.Text = "";
            if ((passwordBox.Text == "") || (usernameBox.Text == ""))
            {
                MessageLabel.Text = "Both a username and a password are required.";
                return;
            }
            if (passwordBox.Text.Length > 25)//password too long - the DB stores up to 25 characters
            {
                MessageLabel.Text = "Max Password length is 25 characters.";
                return;
            }
            if (usernameBox.Text.Length > 25)//username too long max length in the database is 25 characters
            {
                MessageLabel.Text = "Max Username length is 25 characters.";
            }

            // Just a backdoor login so we can navigate the program.
            // I don't care how this is written just as long as it works correctly.
            if (usernameBox.Text == "test" && passwordBox.Text == "test")
            {
                Thread mainMenu = new Thread(() => Application.Run(new MainMenu()));
                mainMenu.Start();

                dbServer = dbServerBox.Text;
                dbPort = dbPortBox.Text;
                dbUsername = dbUsernameBox.Text;
                dbPassword = dbPasswordBox.Text;
                dbDatabase = dbDatabaseBox.Text;

                this.WindowState = FormWindowState.Minimized;
            }

            //Validating their login information with the database
            SQL_Queries login = new SQL_Queries();
            int role = login.validateLogin(usernameBox.Text, passwordBox.Text);

            switch (role)
            {
                case 0:     //Invalid Login
                    MessageBox.Show("Invalid Login");
                    break;

                case 1:     //Admin
                    Thread mainMenuThread = new Thread(() => Application.Run(new AdminMenu()));
                    mainMenuThread.SetApartmentState(ApartmentState.STA);
                    mainMenuThread.Start();
                    this.WindowState = FormWindowState.Minimized;
                    break;

                default:
                    MessageBox.Show("Unknown Error");
                    break;
            }
        }