I need to copy the last added element in my data base to a splist in my site.
The workflow action "Execute SQL", hasn't a trigger on my database. I have to put a specific query.
It that a way to do this , i know on sharepoint there is service BCS , here in nintex how to do it.
depending on the columns in your table, this could get you started: How to read the last row with SQL Server - Stack Overflow
Don't think BCS is of any use here.