Compare 2 lists in Sharepoint

Hi together,

I´ve got a problem. I have two different SharePoint lists, A and B. They both have an article number. I want to check for each cell in list B (article nr.) if it already exists somewhere in column Article nr. in List A. If so, do nothing; if not, add that particular row from list b in list A. The tables have identical columns.

As I am a newbie in Sharepoint, I would love to get some help. Is that possible? I can´t manage it by myself.

Thank you in advance,

~ L4nce