"blob not opened"错误

Question

当我把图片保存到数据库之后,再按table1.next的按钮时,出现上面的错误;而没保存图片以前,按TABLE1.NEXT的按钮,会在IMAGE1出现图片,为什么?????请各位帮帮忙吧.

Answer 1

我把代码付上:
unit Unit2;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,jpeg,
  StdCtrls, ExtCtrls, Db, DBTables, ExtDlgs, DBCtrls;type
  TForm1 = class(TForm)
    Image1: TImage;
    xinjian: TButton;
    next: TButton;
    Database1: TDatabase;
    Table1: TTable;
    prior: TButton;
    save: TButton;
    DataSource1: TDataSource;
    OpenPictureDialog1: TOpenPictureDialog;
    search: TButton;
    procedure xinjianClick(Sender: TObject);
    procedure nextClick(Sender: TObject);
    procedure priorClick(Sender: TObject);
    procedure saveClick(Sender: TObject);
    procedure searchClick(Sender: TObject);
  private
    { Private declarations }
  public
     bm :TjpegImage;
    { Public declarations }
  end;var
  Form1: TForm1;implementationuses Unit3;{$R *.DFM}procedure TForm1.xinjianClick(Sender: TObject);begin
 
if OpenPictureDialog1.Execute then
  begin
     table1.Open;
     table1.Append;
     bm:= TJpegImage.Create;
     bm.LoadFromFile(OpenPictureDialog1.FileName);
     image1.Picture.Graphic := bm;  end;
  
end;procedure TForm1.nextClick(Sender: TObject);
var ms: TStream;
    mb:TjpegImage;
begintry
if table1.Active then
  begin
    table1.next;
  try
  mb:= TjpegImage.Create;
  ms:= Table1.CreateBlobStream(table1.FieldByName('tu'), bmRead);
  mb.LoadFromStream(ms);
  image1.Picture.Assign(mb);
  mb.Free;
  ms.Free;
  except
      ShowMessage('图片显示出错！');
      exit;
    end;
  end;
except
      ShowMessage('数据表没有打开！');
      exit;
    end;
end;procedure TForm1.priorClick(Sender: TObject);
var ms: TStream;
    mb :TjpegImage;
begintry
if table1.Active then
  begin
    table1.Prior;
  try
  mb := TjpegImage.Create;
  ms := Table1.CreateBlobStream(table1.FieldByName('tu'), bmRead);
  mb.LoadFromStream(ms);
  image1.Picture.Assign(mb);
  mb.Free;
  ms.Free;
  except
      ShowMessage('图片显示出错！');
      exit;
  end;
  end;
except
      ShowMessage('数据库没有打开！');
      exit;
    end;
end;procedure TForm1.saveClick(Sender: TObject);
var
  ms: TStream;
begin
 
  try
  ms := Table1.CreateBlobStream(table1.FieldByName('tu'), bmWrite);
  image1.Picture.Graphic.SaveToStream(ms);
  Table1.Post;
  bm.Free;
  ms.Free;
  showmessage('图片保存成功!');
  except
      ShowMessage('图片保存出错或不能保存！');
      exit;
  end;
end;procedure TForm1.searchClick(Sender: TObject);
begin
   form3.show;
end;end.