aStream:TMemoryStream;

aStream:=TMemoryStream.Create;

字段保存到stream

qrypub.ParamByName('Data').LoadFromStream(aStream, ftBlob);

从字段读取到Stream里

  TBlobField(dm.qrypub.FieldByName('FILE_TEXT')).SaveToStream(aStream);

aStream.position:=0;

用完后释放

aStream.Free;

TBlobField *BlobField=(TBlobField *) DataMod->InsertTable->FieldByName("ff");

//文件到字段
TBlobField *blob_pic=(TBlobField *)UserMod->TInsert->FieldByName("IMAGE");
        blob_pic->LoadFromFile(app_path+"//temp//temp.jpg");


//字段到文件
TBlobField *blob_pic=(TBlobField *)DBGrid4->DataSource->DataSet->FieldByName("IMAGE");
    try
    {
        blob_pic->SaveToFile(app_path+"//temp//temp1.jpg");
        Image9->Picture->LoadFromFile(app_path+"//temp//temp1.jpg");

    TMemoryStream * aStream = new TMemoryStream;
                  ((TBlobField*) ADOQuery4->FieldByName("ff"))->SaveToStream(aStream);
                aStream->SaveToFile(SaveDialog1->FileName );