//Thêm loại món ăn vào danh sách
        public Boolean InsertTable(TableDTO lst)
        {
            try
            {
                TABLES_INFO newDishType = new TABLES_INFO() { Id = Guid.NewGuid(), NAME = lst.NAME, CODE = lst.code, WAITER_ID = (from a in Context.WAITER_INFO where a.NAME == lst.WaiterName select a.Id).SingleOrDefault() };

                Context.TABLES_INFO.AddObject(newDishType);
                Context.SaveChanges();
                return true;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
 public Boolean UpdateTable(TableDTO lst)
 {
     try
     {
         TABLES_INFO query = (from p in Context.TABLES_INFO where p.Id == lst.ID select p).SingleOrDefault();
         query.NAME = lst.NAME;
         query.CODE = lst.code;
         query.WAITER_ID=(from a in Context.WAITER_INFO where a.NAME==lst.WaiterName select a.Id).SingleOrDefault();
         Context.SaveChanges();
         return true;
     }
     catch (Exception ex)
     {
         throw ex;
     }
 }
 private void tsbSave_Click(object sender, System.EventArgs e)
 {
     TableDTO dt = new TableDTO();
     if (FormState == FormStateType.New)
     {
         dt.NAME = textBox2.Text.Trim();
         dt.code = Convert.ToInt32(textBox3.Text);
         dt.WaiterName = comboBox1.SelectedValue.ToString();
         repT.InsertTable(dt);
     }
     else if (FormState == FormStateType.Edit)
     {
         dt.ID = PKEY;
         dt.NAME = textBox2.Text.Trim();
         dt.code = Convert.ToInt32(textBox3.Text);
         dt.WaiterName = comboBox1.SelectedText;
         repT.UpdateTable(dt);
     }
     FormState = FormStateType.Normal;
     tsbSave.Enabled = false;
     tsbCancel.Enabled = false;
     tbsAddNew.Enabled = true;
     tsbEdit.Enabled = true;
     tsbDelete.Enabled = true;
     LoadDataBanan();
 }