ASP.NET

<asp:TemplateField HeaderText="Variable Price">
                   <ItemTemplate>
                       <asp:Label ID="tbPrice" Width="100px" runat="server" />
                   </ItemTemplate>
                   <EditItemTemplate>
                       <asp:DropDownList   ID="ddlVariable"

                                           Width="100px"
                                           runat="server"  />


                   </EditItemTemplate>
               </asp:TemplateField>

protected void btnSubmit_Click(object sender, EventArgs e)
        {
            try
            {

                ErrorMessage.Text = "";
                cnx.Open();
                
                SqlCommand insertCmd = new SqlCommand("insert into Coupon_Info(ReceivingDate,Coupon_TypeID,Serial_Start,Serial_End,Recieved_By)values(@date,@CouponId,@Start,@End,@By)",cnx);
                
                
                insertCmd.Parameters.Add("@Date", SqlDbType.DateTime);
                insertCmd.Parameters["@Date"].Value = txtdate.Text;
                
                insertCmd.Parameters.Add("@CouponId", SqlDbType.TinyInt);
                insertCmd.Parameters["@CouponId"].Value = DropDownList1.Text;
                
                insertCmd.Parameters.Add("@Start", SqlDbType.BigInt);
                insertCmd.Parameters["@Start"].Value = txtbxFrom.Text;
                
                insertCmd.Parameters.Add("@End", SqlDbType.BigInt);
                insertCmd.Parameters["@End"].Value = txtbxTo.Text;
                
                insertCmd.Parameters.Add("@By", SqlDbType.NVarChar, 50);
                insertCmd.Parameters["@By"].Value = txtbxBy.Text;
                
                insertCmd.ExecuteNonQuery();
                ErrorMessage.Text = "Successful";
                cnx.Close();
            }
            catch (Exception ex)
            { ErrorMessage.Text = ex.Message; }
        }