存取图片时将二进制流保存到变量时没有实现，求解答,该如何解决

存取图片时将二进制流保存到变量时没有实现，求解答
procedure TForm1.Button1Click(Sender: TObject);
var
  myPicture:TJPEGImage;
  mem:TMemoryStream;

begin
  mem:=TMemoryStream.Create;
  myPicture:=TJPEGImage.Create;
  if(OpenDialog1.Execute()) then
  begin
  mem.LoadFromFile(OpenDialog1.FileName);
  myPicture.LoadFromFile(OpenDialog1.FileName);
  myPicture.SaveToStream(mem);



  with ADOQuery1 do
  begin

  close;
  sql.Clear;
  sql.Add('insert into imagetest (imgid,imgsize) values(1,"+mem+")');
  // TBlobField(ADOQuery1.FieldByName('imgsize')).SaveToStream(mem);
  ExecSQL;
  end;
  mypicture.Free;
  mem.Free;
end;
end;
其中myPicture.LoadFromFile(OpenDialog1.FileName);
  myPicture.SaveToStream(mem);
是想将用OpenDialog打开的图片二进制流存入变量mem中，但运行时mem为空，求各位大虾帮忙

------解决方案--------------------------------------------------------
这是delphi，不是delphi.net，还是去开发语言-delphi问吧。