Distinct count or select across several columns

[miruna_a]

Hi!

I have a table with three columns. I want to be able to count all the unique values across the 3 columns. Basically, in the end, I would like to have a column with each ID found in the 3 previous ones, but only once (thus, only have unique values) - a column with the total number of unique values, from the 3 initial ones.

Any ideas on how to do that or whether it’s possible to do it?

Thanks a lot!