查询数据库中的表建个进度条

这段代码不是我自己写的,呵呵,是李维书上的.直接编译附件里的工程就可以看到效果了.unit fDemoMain;interfaceuses  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,  ComCtrls, Grids, DBGrids, ExtCtrls, DBCtrls, Db, ADODB, StdCtrls;type  TForm1 = class(TForm)    ADOConnection1: TADOConnection;    ADODataSet1: TADODataSet;    DataSource1: TDataSource;    DBNavigator1: TDBNavigator;    DBGrid1: TDBGrid;    ADOCommand1: TADOCommand;    ProgressBar1: TProgressBar;    Button1: TButton;    Button2: TButton;    procedure FormActivate(Sender: TObject);    procedure ADODataSet1FetchProgress(DataSet: TCustomADODataSet;      Progress, MaxProgress: Integer; var EventStatus: TEventStatus);    procedure Button2Click(Sender: TObject);    procedure Button1Click(Sender: TObject);    procedure ADODataSet1FetchComplete(DataSet: TCustomADODataSet;      const Error: Error; var EventStatus: TEventStatus);  private    { Private declarations }    lStart : Longint;    lEnd : Longint;  public    { Public declarations }  end;var  Form1: TForm1;implementation{$R *.DFM}procedure TForm1.FormActivate(Sender: TObject);var  sRecNo : String;begin  ProgressBar1.Max := ADOCommand1.Execute.Fields.Item[0].Value;  sRecNo := IntToStr(ProgressBar1.Max);  Self.Caption := '共有' + sRecNo + ' 笔资料';end;procedure TForm1.ADODataSet1FetchProgress(DataSet: TCustomADODataSet;  Progress, MaxProgress: Integer; var EventStatus: TEventStatus);begin  ProgressBar1.Position := Progress;end;procedure TForm1.Button2Click(Sender: TObject);begin  try    ADODataSet1.Active := False;    ADODataSet1.ExecuteOptions := [eoAsyncFetchNonBlocking];  finally    lStart := GetTickCount;    ADODataSet1.Active := True;  end;end;procedure TForm1.Button1Click(Sender: TObject);begin  try    ADODataSet1.Active := False;    ADODataSet1.ExecuteOptions := [eoAsyncFetch];  finally    lStart := GetTickCount;    ADODataSet1.Active := True;  end;end;procedure TForm1.ADODataSet1FetchComplete(DataSet: TCustomADODataSet;  const Error: Error; var EventStatus: TEventStatus);begin  lEnd := GetTickCount;  ShowMessage('总共花了' + FloatToStr((lEnd - lStart) / 1000.0) + '秒');end;end.