<asp:FormView ID="clienteFormView" runat="server" DefaultMode="Edit" OnDataBound="clienteFormView_DataBound" OnPreRender="clienteFormView_PreRender">
  <EditItemTemplate>
   Nota <asp:TextBox ID="NotaTextBox" runat="server" Text='<%# Bind("Nota") %>' Style="margin-right: 12px" />
   Tipo Pagamento <asp:DropDownList ID="pagamentiDropDownList" runat="server" DataTextField="Descrizione" DataValueField="CodPag" SelectedValue='<%# Bind("CodPag") %>'></asp:DropDownList>
   </EditItemTemplate>
</asp:FormView>

protected void Page_Load(object sender, EventArgs e)
{ var clientRecord = client.Clients_GetById(idAnag);
  clienteFormView.DataSource = clientRecord.Records;
  clienteFormView.DataBind();}

DropDownList pagamentiDropDownList = clienteFormView.FindControl("pagamentiDropDownList") as DropDownList;