private void btnLogin_Click(object sender, EventArgs e)
 {
     if (TaiKhoanData.CheckLogin(txtUsername.Text.Trim().ToString(), txtPassword.Text))
     {
         lblInvalid.Visible = false;
         this.Visible       = false;
         frmMaintainSpeciality form = new frmMaintainSpeciality();
         form.LoginedUser = txtUsername.Text.Trim().ToString();
         form.Visible     = true;
     }
     else
     {
         lblInvalid.Visible = true;
     }
 }
 public frmAddUpdateSpeciality(frmMaintainSpeciality maintainForm, bool isNew, Khoa khoa = null) : this()
 {
     if (isNew)
     {
         txtSpecialtityFoundedYear.Visible = false;
         lblYear.Visible = false;
         txtSpecialtityFoundedYear.Text = DateTime.Now.Year.ToString();
         txtSpecialityCode.Text         = string.Empty;
         txtSpecialityName.Text         = string.Empty;
     }
     else
     {
         txtSpecialityCode.Text         = khoa.MaKhoa;
         txtSpecialityName.Text         = khoa.TenKhoa;
         txtSpecialtityFoundedYear.Text = khoa.NamThanhLap + "";
         //txtSpecialityCode.Enabled = false;
     }
     this.isNew        = isNew;
     this.maintainForm = maintainForm;
     this.Text         = isNew ? "Thêm mới khoa" : "Chỉnh sữa khoa";
 }