the syntax :

Class1:

public void btnLogin_Click(object sender, RoutedEventArgs e)
        {
            if (isValid()) 
            {
                SqlCommand cmd = new SqlCommand("SELECT COUNT(1) FROM usertb WHERE username=@username AND pass_word=@pass_word", con);
                cmd.CommandType = System.Data.CommandType.Text;
                cmd.Parameters.AddWithValue("@username", txtUser.Text);
                cmd.Parameters.AddWithValue("@pass_word", txtPass.Password);
                con.Open();

                int count = Convert.ToInt32(cmd.ExecuteScalar());

                SqlCommand cmd1 = new SqlCommand("SELECT usr_id ,userType FROM usertb WHERE username=@username AND pass_word=@pass_word", con);
                cmd1.CommandType = System.Data.CommandType.Text;
                cmd1.Parameters.AddWithValue("@username", txtUser.Text);
                cmd1.Parameters.AddWithValue("@pass_word", txtPass.Password);

                SqlDataReader reader1;
                reader1 = cmd1.ExecuteReader();
                string userType = "";
                string y1 = "1";


                if (reader1.Read()) 
                {
                    string userID = reader1["usr_id"].ToString();
                    string v = reader1["userType"].ToString();
                    value = y;
                    userType = v;


                }
                
                CurriculumControl curriculumControl = new CurriculumControl();
                curriculumControl.SetUserId(y1);


                con.Close();
                if (count == 1 && userType == "Admin")
                {
                    MainInterface dashboard = new MainInterface();
                    LoginView loginView = new LoginView();

                    

                    


                    dashboard.Show();
                    this.Visibility = Visibility.Collapsed;

                    CurriculumControl passID = new CurriculumControl();
                    
                    


                }
                else 
                {
                    MessageBox.Show("Username or password is incorrect");
                }
                //cmd.ExecuteNonQuery();
                
                Console.WriteLine(count);
                
            }

        }


i plan the userID to get stored in a variable in another class but the output is always null in the second class

userID has value but when i pass it in another class it becomes null