Cannot create percentage columns in CartoDB

[peterdesmet]

I'm stumped. For some reason, CartoDB let's me create percentage columns as such:

SELECT
*,
round((section_1/total*100)::numeric,2) as section_1_pct
FROM municipalities_blackout

But nothing happens if I select that column in the choropleth wizard. If I try to export the data, it's all empty. If I try to create a table of the view, I get a 8003 error, warning me about duplicate columns.

[peterdesmet]

Total can be zero, which would divide by zero. CartoDB does show the column, but all the rest doesn't work. Can be solved with a CASE.