Updating data.table by inserting new rows that are different from old rows

Question

I have two data.table(dt1 & dt2). dt1 is past product data and dt2 is present product data. I want to create a third data.table that inserts new rows from dt2 into dt1 only

Answer 1

You can stack and uniqify:

unique(rbind(dt1, dt2), by=c("Product", "Level", "Color"))