Why I cann't update one column by details View Control.

Question

Greeting

I designed a senario to update employee information [salary, position, photo and etc].

a normal scinario when I select user open details view and get all colums and a user updated what is required to update.

But I make new scinario : Just open details view in [Read only mode] to update image only if that required and if required more details click on edit button and then change [details view] from [Read only mode] to [edit mode].

 

a problem is an update button code an want to update employee imagem see a code below:

 

<ItemTemplate>
    <asp:ImageButton ID="ImageButton1" runat="server" BorderColor="#CC0000" BorderStyle="Dashed" BorderWidth="1px" Height="130px" ImageUrl='<%# Eval("S_photo") %>' OnCommand="ImageButton1_Command" Width="130px" />
    <asp:FileUpload ID="FileUpload_EmpPhoto" runat="server" />
    <asp:Button ID="Button1" runat="server" CausesValidation="False" OnCommand="Button1_Command" Text="Update" />
    <asp:Label ID="Modal_Lb_Status" runat="server"></asp:Label>
</ItemTemplate>

 Code behind here:

protected void Button1_Command(object sender, CommandEventArgs e)
  {
      Label lb_Info = (Label)DV_StafdUpade.FindControl("Modal_Lb_Status");
      FileUpload FEmpNewImg = (FileUpload)DV_StafdUpade.FindControl("FileUpload_EmpPhoto");

          if (FEmpNewImg.HasFile)
          {
              string fileName = FEmpNewImg.FileName;
              string exten = Path.GetExtension(fileName);

              FEmpNewImg.SaveAs(Server.MapPath("~/images/staff/" + Path.GetFileName(fileName)));
              string link = "~/images/staff/" + Path.GetFileName(fileName);
              using (SqlConnection sqlcon = new SqlConnection(Constr))
              {

              //Open Connection with D.B
              sqlcon.Open();
              string query = "UPDATE Staff SET [S_photo]= @S_photo WHERE (Staff.UserId = @UserId)";
              SqlCommand sqlcmd = new SqlCommand(query, sqlcon);
              sqlcmd.Parameters.AddWithValue("@S_photo", link);
              sqlcmd.ExecuteNonQuery();
              sqlcmd.Dispose();
              sqlcon.Close();
              //DV_StafdUpade.DataBind();
              lb_Info.Text = "Employee image has been updated Successfully.";
              lb_Info.ForeColor = System.Drawing.Color.Green;
              lb_Info.BorderColor = System.Drawing.Color.Green;
              }//End Using
          }//End Main If (file upload) has file

  }

So what do you think:

1) a problem I cann't update one column in [Read only mode] till if I desgined a command to update.

 

Thanks