private void btnBack_Click(object sender, EventArgs e)
        {
            //Create a new instance of the Studio2Menu screen.
            Studio2Menu studio2Menu = new Studio2Menu();

            //Show the Studio2Menu screen.
            studio2Menu.Show();
            //Hide this screen.
            Hide();
        }
 //Create click event for btnEnter.
 private void btnEnter_Click(object sender, EventArgs e)
 {
     //If txtUsername is not empty...
     if (txtUsername.Text != "")
     {
         //If txtPassword is not empty...
         if (txtPassword.Text != "")
         {
             //This section of code ensures that whatever StaffID is entered into the textbox is valid.
             using (SqlConnection connection = new SqlConnection(_connectionString))
             {
                 using (SqlCommand sqlCommand = new SqlCommand("SELECT COUNT(*) FROM Staff WHERE (StaffID = @StaffID)", connection))
                 {
                     connection.Open();
                     sqlCommand.Parameters.AddWithValue("@StaffID", txtUsername.Text);
                     int    user      = (int)sqlCommand.ExecuteScalar();
                     bool   userExist = false;
                     string staffID   = txtUsername.Text;
                     int    _staffID  = int.Parse(txtUsername.Text);
                     string password  = txtPassword.Text;
                     if (user > 0)
                     {
                         //If the password enters matches "Admin_Studio2"...
                         if (password == "Admin_Studio2")
                         {
                             //Set the userExist variable to true.
                             userExist = true;
                             //If userExist is true...
                             if (userExist)
                             {
                                 //Create a new instance of the Studio2Menu screen.
                                 Studio2Menu studio2Menu = new Studio2Menu();
                                 //Show the Studio2 Menu screen.
                                 studio2Menu.Show();
                                 //Hide the Studio2 Menu screen.
                                 Hide();
                             }
                             //Otherwise, display a message telling the user that the username is invalid.
                             else
                             {
                                 MessageBox.Show("Invalid username.");
                             }
                             //Otherwise, display a message telling the user that the password is incorrect.
                         }
                         else
                         {
                             MessageBox.Show("Incorrect password.");
                         }
                     }
                     //Otherwise, display a message telling the user that the username is invalid.
                     else
                     {
                         MessageBox.Show("Invalid Username.");
                     }
                 }
             }
         }
         //Otherwise, display a message asking the user to enter a password.
         else
         {
             MessageBox.Show("Please enter a password.");
         }
     }
     //Otherwise, display a message asking the user to enter a username.
     else
     {
         MessageBox.Show("Please enter a username.");
     }
 }