Replacing nulls when adding across columns
I have a table which contains null values, and I want to get a dynamic (i.e. it responds to filters - therefore has to be done in beast mode, as I understand) total of values across three columns, keeping null values in the orignal columns but treating them as '0's for the purpose of the calculation. I have tried several methods none of which work, my most recent attempt is:
(case when LENGTH(`2016`) = 0 then 0 else `2016` end)+
(case when LENGTH(`2017`) = 0 then 0 else `2017` end)+
(case when LENGTH(`2018`) = 0 then 0 else `2018` end)
Can anyone point out where I am going wrong? For context, I want to use the new column ultimately to calculate a % of grand total (of displayed data), and belive this is the first step.