var
     filename:string;//目标文件名。
     source,target: TFileStream;
begin
     source:=TFileStream.Create('源文件.mdb',fmOpenRead );
     try
       target:=TFileStream.Create(filename,fmOpenWrite or fmCreate);
       try
         if target.CopyFrom(source,source.Size)=source.Size then
           ShowMessage('成功备份到'+filename+'!!!');
       finally
         target.Free;
       end;
     finally
       source.Free;
     end;