动态绑定和主细表——Fetch

Fetch是SDK里自带的sample，描述了如何创建主细表结构并动态获取数据。

第一步，创建主细表。在schema中添加表orders和order details，回到客户端右击tbl_OrderDetails启动主细表向导:

选择DataSource和MappingMode:

点击Next选择描述主细表关系的字段:

点击Next完成向导。这样第一步对表结构的构架就已经完成。

第二步，如何实现动态绑定表数据。

1，在主表orders里字段pa'rams设置StartingOrderID

2，打开schema，设置两个字段的属性一样

3，编辑tbl_orders事件afterScoll

procedure TClientForm.tbl_OrdersAfterScroll(DataTable: TDADataTable);
var
  lrecordcount: integer;
begin
  if fFetchRequired and DataTable.EOF and not DataTable.Fetching then
    with DataTable do begin
      ParamByName('StartingOrderID').AsInteger := FieldByName('OrderID').AsInteger;
      MaxRecords := strtoint(edit1.text);
      lrecordcount := DataTable.RecordCount;
      LoadFromRemoteSource(True);
      lrecordcount := RecordCount-lrecordcount;
      fFetchRequired := lrecordcount = MaxRecords;
      if not fFetchRequired then
        MessageDlg(Format('Done fetching!!! Expected %d rows but only got %d ',
                          [MaxRecords, lrecordcount]), mtInformation, [mbOK], 0);
    end;
end;

4，FILL按钮

procedure TClientForm.Button1Click(Sender: TObject);
begin
  if not tbl_Orders.Active then begin
    tbl_Orders.ParamByName('StartingOrderID').AsInteger := 0;
    tbl_Orders.MaxRecords := strtoint(edit1.text);
    fFetchRequired := True;
  end;
  tbl_Orders.Active := not tbl_Orders.Active
end;