private void buttonGuestLogin_Click(object sender, EventArgs e)
        {
            login = "******";
            LibraryScreen menuGuest = new LibraryScreen();

            menuGuest.Login = login;
            menuGuest.Show();
        }
        private void buttonLogin_Click(object sender, EventArgs e)
        {
            login = "******";
            string              cnS = "data source=(local);initial catalog=SA47_Team12aCADatabase;integrated security=SSPI";
            SqlConnection       cn  = new SqlConnection(cnS);
            string              sql = "Select Login,Password from EmployeeMaster";
            SqlCommand          cm  = new SqlCommand(sql, cn);
            SqlDataAdapter      da  = new SqlDataAdapter(cm);
            SqlCommandBuilder   cmb = new SqlCommandBuilder(da);
            SA47_Team12bDataSet ds  = new SA47_Team12bDataSet();

            da.Fill(ds, "EmployeeMaster");
            DataRow dr = ds.Tables["EmployeeMaster"].NewRow();
            int     a, b = 0;

            for (a = 0; a < ds.Tables["EmployeeMaster"].Rows.Count; a++)
            {
                if (ds.Tables["EmployeeMaster"].Rows[a]["Login"].ToString() == textBoxUsername.Text.Trim())
                {
                    break;
                }
                if (a == ds.Tables["EmployeeMaster"].Rows.Count)
                {
                    a = 109;
                }
            }
            if (a < ds.Tables["EmployeeMaster"].Rows.Count)
            {
            }

            else
            {
                MessageBox.Show("User not found!!");
            }
            for (b = 0; b < ds.Tables["EmployeeMaster"].Rows.Count; b++)
            {
                if (ds.Tables["EmployeeMaster"].Rows[b]["Password"].ToString() == textBoxPassword.Text.Trim())
                {
                    break;
                }
            }
            if (b < ds.Tables["EmployeeMaster"].Rows.Count)
            {
            }

            else
            {
                MessageBox.Show("Password not correct!!");
            }
            if (a == b && textBoxUsername.Text != "" && textBoxPassword.Text != "")
            {
                LibraryScreen menus = new LibraryScreen();
                menus.Showname = textBoxUsername.Text;
                menus.Show();
                this.Hide();
            }
            else if (b < ds.Tables["EmployeeMaster"].Rows.Count)
            {
                MessageBox.Show("Password not correct!!");
            }
        }