เขียน code update ค่ะ แต่ข้อมูลไม่ยอม update ลงในฐานข้อมูลค่ะ asp.net c#

protected void Button1_Click(object sender, EventArgs e)
        {
            
            HyperLink LabelNo;
            HyperLink LabelId;
           
            int i;
          
            Label3.Text = "";
            Label4.Text = "";
            Label5.Text = "";
            Label6.Text = "";
            Label7.Text = "";
            for (i = 0; i <= GridView1.Rows.Count - 1; i++)
            {
              
                LabelNo = (HyperLink)GridView1.Rows[i].FindControl("htno");
                LabelId = (HyperLink)GridView1.Rows[i].FindControl("htid");
                 DropDownList DropDownList1 = (DropDownList)this.GridView1.Rows[i].FindControl("DropDownList1");
             


                this.Label3.Text = this.Label3.Text + "<br>" + LabelNo.Text;
                this.Label6.Text = this.Label6.Text + "<br>" + LabelId.Text;
                this.Label4.Text = this.Label4.Text + "<br>" + DropDownList1.Text;
           

                if (this.RadioButton1.Checked == true)
                {
                    this.Label7.Text = this.Label7.Text + "<br>" + "สมบูรณ์";
                }
                if (this.RadioButton2.Checked == true)
                {
                    this.Label7.Text = this.Label7.Text + "<br>" + "ไม่สมบูรณ์";
                }

                //Code update
                string StrConn2 = WebConfigurationManager.ConnectionStrings["connection"].ToString();
                SqlConnection Conn2 = new SqlConnection(StrConn2);
                Conn2.Open();
                string sqlProduct2;

                sqlProduct2 = "UPDATE snack SET" + 
                    " Note = '" + this.Label4.Text + "' " +
               " WHERE  Id= '" +   this.Label6.Text + "' ";
                SqlDataAdapter da = new SqlDataAdapter(sqlProduct2, Conn2);
    
            }
           
    }