QByteArray s = query.value(nameCol).toByteArray();//读取二进制对象
this is a example to write a pixmap into database
QByteArray pngImage;
QBuffer buffer(&pngImage);
buffer.open(QIODevice::WriteOnly);
upimage.save(&buffer, "PNG"); // writes upimage into bytes in PNG format
......
query.bindValue(7,pngImage,QSql::Binary);