function GetBlobFieldData(FieldNo: Integer; var Buffer: TBlobByteData): Integer; override; 要怎麼用.....

這個function 好像真的滿少資料 而且我也不知道您是那一個元件的GetBlobFieldData 參考看看吧 TDataSet::GetBlobFieldData GetBlobFieldData reads blob data from the field specified by FieldNo into a Buffer. The buffer is a dynamic array of bytes, so that it can grow to accommodate the size of the BLOB data. GetBlobFieldData returns the size of the buffer. TCustomADODataSet::GetBlobFieldData Most applications do not need to call GetBlobFieldData, this method being used internally by descendants of TCustomADODataSet. GetBlobFieldData reads blob data from the field specified by FieldNo into a Buffer. The buffer is a dynamic array of bytes, so that it can grow to accommodate the size of the BLOB data. GetBlobFieldData returns the size of the buffer. TBDEDataSet::GetBlobFieldData GetBlobFieldData reads blob data from the field specified by FieldNo into a Buffer. The buffer is a dynamic array of bytes, so that it can grow to accommodate the size of the BLOB data. GetBlobFieldData returns the size of the buffer.

很简单呀，你定义一个TBlobByteData类型的变量就行了，如

var
  AData:TBlobByteData;
begin
  ADOQuery1.Open;
  ADOQuery1.GetBlobFieldData(2,AData);

你看看delphi的DB.pas的原码:

function TDataSet.GetBlobFieldData(FieldNo: Integer; var Buffer: TBlobByteData): Integer;
var
  Stream: TStream;
begin
  Stream := CreateBlobStream(FieldByNumber(FieldNo) as TBlobField, bmRead);
  try
    Result := Stream.Size;
    if Result > 0 then
    begin
      if Length(Buffer) <= Result then
        SetLength(Buffer, Result   Result div 4);
      Stream.Read(Buffer[0], Result);
    end;
  finally
    Stream.Free;
  end;
end;

它自己跟你分配AData的大小，不用考虑够不够。剩下的问题是看你如何使用AData,你也可以这样获得blob的资料:

var
  MS:TMemoryStream;
begin
  ADOQuery1.Open;
  MS:=TMemoryStream.Create;
  TBlobField(ADOQuery1.Fields[2]).SaveToStream(MS);

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