I have multiple shapefile layers of a city with its districts that have the same shape and information, only the last two columns are different (The picture shows one of the three attribute tables).
Now I want to add up the last column (contains numbers from 1-5) of each shapefile and write the result in a new layer that has the same shape. I thought about using "Merge vector layers" and then using the Field Calculator to sum up the columns but the algorithm adds new rows with the districts so I end up with three times as many districts whereas I need three new columns with the numbers so I can add them up.