ClientDataSet中撤消与恢复操作及执行细节

procedure TForm3.Button2Click(Sender: TObject);
begin
  //未POST前，取消操作
  ClientDataSet1.Cancel;
  ViewXMLData;
end;
 
procedure TForm3.Button3Click(Sender: TObject);
begin
  //取消当前条记录的操作
  //会操作CHANGE_LOG，并减少ChangCount计数
  ClientDataSet1.RevertRecord;
  ViewXMLData;
end;
 
procedure TForm3.Button4Click(Sender: TObject);
begin
  //可连续撤消操作，直到 CHANGE_LOG为空，并减少ChangCount计数
  ClientDataSet1.UndoLastChange(true);
  ViewXMLData;
end;
 
procedure TForm3.Button5Click(Sender: TObject);
begin
  //post后撤消操作,CHANGE_LOG会被清空，ChangCount被置0
  //一只撤消本地的全部操作
  ClientDataSet1.CancelUpdates;
  ViewXMLData;
end;
 
procedure TForm3.Button6Click(Sender: TObject);
begin
  //合并修改日志，合并后CHANGE_LOG会被清空，ChangCount被置0
  //合并后UNDO功能无效
  ClientDataSet1.MergeChangeLog;
  ViewXMLData;
end;
 
procedure TForm3.Button7Click(Sender: TObject);
begin
  //设置还原点
  tempPoint := ClientDataSet1.SavePoint;
  ViewXMLData;
end;
 
procedure TForm3.Button8Click(Sender: TObject);
begin
  //恢复还原点
  ClientDataSet1.SavePoint := tempPoint;
  ViewXMLData;
end;
 
procedure TForm3.ClientDataSet1AfterPost(DataSet: TDataSet);
begin
  ViewXMLData;
end;
 
procedure TForm3.ViewXMLData;
begin
  Text := Format(‘ChangeCount: %d‘, [ClientDataSet1.ChangeCount]);
  // uses XMLDoc单元
  Memo1.Text := FormatXMLData(ClientDataSet1.XMLData);
end;
 
procedure TForm3.Button1Click(Sender: TObject);
begin
  ViewXMLData;
end;