private void tbTen_Leave(object sender, EventArgs e)
        {
            tbTen.Text = TienIch.ToTitleCase(tbTen.Text);
            string sqlSelect = "Select Ten from Thuoc where Ten=N'" + tbTen.Text + "'";

            if (DataBaseFunction.IsExisted(sqlSelect))
            {
                TienIch.ShowCanhBao("Cảnh Báo", "Thuốc này đã tồn tại trong csdl");
                tbTen.SelectionLength = tbTen.Text.Length;
            }
        }
        private void AddCongDungChoThuoc(string tenThuoc)
        {
            string sqlSelect = "Select Id from Thuoc where Ten=N'" + tenThuoc + "'";
            int    thuocId   = DataBaseFunction.GetItemId(sqlSelect);

            List <int> danhSachCongDung = new List <int>();

            foreach (string item in clbCongDung.CheckedItems)
            {
                string sqlSelectId = "Select Id from CongDung where Ten=N'" + item + "'";
                danhSachCongDung.Add(DataBaseFunction.GetItemId(sqlSelectId));
            }

            foreach (int idCongDung in danhSachCongDung)
            {
                if (!DataBaseFunction.IsExisted("Select * from ThuocCongDung where IdThuoc=" + thuocId + " and IdCongDung=" + idCongDung))
                {
                    string sqlInsert = "Insert into ThuocCongDung(IdThuoc,IdCongDung) values(" + thuocId + "," + idCongDung + ")";
                    DataBaseFunction.ExcuteSQL(sqlInsert);
                }
            }
        }