[ C# ]-- The name "af" is not permitted in this context. (ใครเคยเจอบ้างครับ มึนตึ้บ)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;


namespace Accounting
{
    public partial class allowance : Form
    {
     
        private string backvalue;
        public string BackedValue
        {
            get { return backvalue; }
            set { backvalue = value; }
        }
        public allowance()
        {
            InitializeComponent();
        }

        private void label3_Click(object sender, EventArgs e)
        {

        }

        private void allowance_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
             SqlConnection objConn = new SqlConnection();
            SqlCommand objCmd = new SqlCommand();
            //ประกาศตัวแปร ที่ใช้ได้ใน button นี้ 
            String strConnString, strSQL;
            //
            strConnString = "Server=XXXX;UID=XXXXX;PASSWORD=XXXX;database=XXXX;Max Pool Size=400;Connect Timeout=600;";
            objConn = new System.Data.SqlClient.SqlConnection(strConnString); //systax sql แบบเว็บ
            objConn.Open();
            //SQL ทำงาน

            strSQL = "INSERT INTO FLST_EXPENSE_ALLOWANCE (allowance_date,allowance_work_order_id,allowance_driver_name,allowance_driver_id,allowance_start_job,allowance_end_job,allowance_wait_id,allowance_rate,allowance_bonus,allowance_remark,allowance_fivety_percent,allowance_twenty_percent) " + 
                                                         "VALUES (@adate,@awid,@adname,@adid,@asj,@aej,@awi,@ar,@ab,@remark,af,at)";
            objCmd = new SqlCommand(strSQL, objConn); //systax sql แบบ winform
            

            //Insert ค่าจาก Textbox ลง Parameter ที่ Declare มาจาก strSQL
           
            objCmd.Parameters.Add(new SqlParameter("@adate", allowance_date.Text));
            objCmd.Parameters.Add(new SqlParameter("@awid", tb_worder.Text));
            objCmd.Parameters.Add(new SqlParameter("@adname", tb_dname.Text));
            objCmd.Parameters.Add(new SqlParameter("@adid", tb_did.Text));
            objCmd.Parameters.Add(new SqlParameter("@asj", tbstart.Text));
            objCmd.Parameters.Add(new SqlParameter("@aej", tbstop.Text));
            objCmd.Parameters.Add(new SqlParameter("@awi", tbwait.Text));
            objCmd.Parameters.Add(new SqlParameter("@ar", tbrate.Text));
            objCmd.Parameters.Add(new SqlParameter("@ab", cbo_bonus.Text));
            //objCmd.Parameters.AddWithValue("@ar", int.Parse(tbrate.Text.Trim()));
            objCmd.Parameters.Add(new SqlParameter("@remark", tb_remark.Text));

            //ประกาศตัวแปล พร้อมใส่ค่า
           
            string sqlquery = ("SELECT TOP 1 * FROM FLST_EXPENSE_ALLOWANCE ORDER BY ALLOWANCE_ID DESC");

            SqlCommand command = new SqlCommand(sqlquery, objConn);
            
                       

            if (this.check_half.Checked == true)
            {
                double anInteger;
                double anInteger2;

                anInteger = Convert.ToDouble(tbrate.Text);
                anInteger2 = anInteger * 0.5;
                objCmd.Parameters.AddWithValue("@af", anInteger2);
                lbl_half.Text = "โบนัสเพิ่ม"+anInteger2.ToString();
                
            }
            else
            {
                this.lbl_half.Text = "ไม่เพิ่มโบนัส";

                objCmd.Parameters.AddWithValue("@af", DBNull.Value);
                
            }
            if (this.check_twenty.Checked == true)
            {
                double anInteger;
                double anInteger2;

                anInteger = Convert.ToDouble(tbrate.Text);
                anInteger2 = anInteger * 0.2;
                objCmd.Parameters.AddWithValue("@at", anInteger2);
                lbl_twenty.Text = "โบนัสเพิ่ม" + anInteger2.ToString();
               
            }
            else
            {
                this.lbl_twenty.Text = "ไม่เพิ่มโบนัส";

               objCmd.Parameters.AddWithValue("@at", DBNull.Value);
                
            }

            
                
                
                DialogResult dialogResult = MessageBox.Show("คุณต้องการจะเพิ่มข้อมูลเบี้ยเลี้ยงใช่หรือไม่", "Some Title", MessageBoxButtons.YesNo);
                if (dialogResult == DialogResult.Yes)
                {
                    
                    objCmd.ExecuteNonQuery();
                    allowance_id.Text = command.ExecuteScalar().ToString();
                    MessageBox.Show("เพิ่มข้อมูลเรียบร้อย");
                }
                else if (dialogResult == DialogResult.No)
                {
                    MessageBox.Show("ยกเลิกการเพิ่มข้อมูล");
                }


                objCmd = null;

                objConn.Close();
                objConn = null;
                
            }
        }
    }