compare two files and match id

thanks both of you, both are working!

Now a further 2 questions.

1) When dragged down, those rows that do not have a id assigned appear as #N/A. How can I just have these as blank?

2) The formula obviously connects book1 and book2. So i assume if I delete book1 then book2 will fail.

After I have got the values I want in book2 I dont actually want to keep a link between the files. I just want the data standalone in book2 - how do i go about doing this?