Question

insert items (ean)
select ean
from books
where ean not in (select ean from mrs..items)

Assume there are duplicates in books. Will sql determine which records to insert upfront and then continue to insert duplicates; or will it prevent itself from inserting duplicates by checking as it goes along?

Answer 1

This should work

insert into items (ean) 
select Distinct ean 
from books