check multiple columns to avoid duplicates

[BenjaminJ]

Hello,

First, thank you to all this community where we learn a lot.
My English is very bad, I will try to be as clear as possible.

Despite my research on the forum, I did not find what I needed.

I'm working on an application to assign employees to shifts per day with role (CI PSP 1, CS ...). I need the form to report that there is a duplicate. For that I think to go through Valid_if, but I can't make him understand that he must check all the columns (CS, CI PSP 1, PSE 2 PSP 1, ...) despite all the indications I have could find on the forum.

Can you accompany me?

Thanks 🙂