Trillium

Greetings, 

I am trying to evaluate certain parameters in Trillium Discovery on a table with duplicates and few columns . Usually in sql statement I use 

Select distinct
id,
nvl(col1, col2) as rate

from table
where state = 'Active'

while filter expressions are pretty clear in trillium, I am struggling to implement distinct and nvl functionalities and didn't find anything (or missed) in the documentation.
Anybody can advice how this can be implemented in expression builder?

Thanks