sql server2k的image字段问题

Question

我有一张表有个image字段用来放图片
格式是 jpg 或者 bmp
但是并没有 其他字段 标志image字段里面存放的图片格式是jpg 还是 bmp现在我在程序中用，怎么判断image字段中放的是jpg 还是 bmp格式的图片？？或者我把字段内容读到流中，怎么能从流中判断它的格式么？？要是可以 怎么判断？？？delphi中的image控件能从流中显示图片么？？？要是可以 怎么显示？？急  急  急大虾 救救 小弟我呀！！！ 谢谢

Answer 1

procedure     TForm1.Button3Click(Sender:     TObject);       
  Var       
        JPGImage:TjpegImage;       
        Bitmap:TBitmap;       
        Stream         :     TMemoryStream;       
        FileName:String;       
        ExtName:     string;       
  begin       
        JPGImage:=TJpegImage.Create;       
        //打开图象文件       
        if     OpenPictureDialog1.Execute     Then       
                begin       
                        FileName:=OpenPictureDialog1.FileName;       
                        ExtName:=AnsiUpperCase(ExtractFileExt(FileName));     //后缀名       
                              
                        //JPGImage加载图象。对两种类型的图象文件：.BMP和.JPG分别处理       
                        if     ExtName='.BMP'     then       
                                begin       
                                        Bitmap:=TBitmap.Create;       
                                        Bitmap.LoadFromFile(FileName);       
                                        JPGImage.Assign(Bitmap);       
                                        JPGImage.Compress;         //压缩成JPEG格式       
                                        Bitmap.Free;       
                                end;       
                              
                        if     ExtName='.JPG'     Then       
                                JPGImage.LoadFromFile(FileName);       
      
                        //JPG图象保存到数据库，要以MemoryStream为中介       
                        Stream:=     TMemoryStream.Create     ;       
                        JPGImage.SaveToStream(Stream);       
                              
                        table1.append;       
                        table1FileName.asstring:=ExtractFileName(FileName);       
                        table1Blob.LoadFromStream(Stream);       
                        table1.Post;       
                              
                        Image1.Picture.Assign(JPGImage);       
                        Stream.Free     ;       
                end;       
              
  end;

Answer 2

楼上说的 是 保存的时候， 如果是bmp格式的就转化成jpg后再保存到数据库中我想问的是，表中已经存在bmp和jpg 两种格式的取出来的时候，怎么判断 它的格式呀。因为image1.picture.assign(adoquery1.fieldbyname('mypic')) 显示的时候 如果是jpg的就出现异常实在不能事先判断 我就用try
如果出错 就说明是jpg格式的

Answer 3

只能用你说的try
再查查资料吧