I am trying to develop an expression whereby one layer can add data from 2 other layers and then rank them, is this possible? I have also tried the problem with using just 1 layer but I cannot work out an expression.
Example: I have 3 layers called "Tech", "Pol" and "Rank". All 3 layers contain a column 'Area' which has fields listing areas of a country. "Tech" and "Pol" both contain an integer column called 'T_col' and 'P_col' respectively and have fields containing data.
Problem: I would like the "Rank" column to add the fields in 'T_col' and 'P_col' and then sorting the order from least to most.
It's coming up with an expression that's confusing me, I don't know if it's possible to calculate data from other layers, hence why I don't mind using just the one.
I have created one layer with this columns and used the Expression String Builder to add up the 2 columns from "Tech" and "Pol". However, I am unsure as to how to include the result into the "rank" column. I tried using a simple code which is not recognised:
"rank" = "T_col" + "P_col"