I created a virtual field in my layer where I want a specific value to be calculated. In my attribute table I have several columns. The expression I am trying to create is the following. I want to iterate through all features and add all values of the
column age who have a specific value, let's say the name of the features should be marc. In my first attempt I created this:
CASE WHEN "name" = "marc" THEN sum( "age" ) END
But it kinda doesn't work and I don't know how to iterate though all features in the layer and only choose those features with the name marc. Any advice?