So I want to combine all the polygons that share two different attribute values and don't really know where to start.
The selection shows you my problem, they both have the same classification (890) and belong to the same block (third column). I want these (and all other similar occurences) to be considered a single multipart polygon. How?
The regular singlepart to multipart tool won't do me any good since I will loose either classification field or the block id field.