Can you please tell me the names of the items that did not receive any reviews?
select title from item where i_id not in ( select i_id from review )
What are their item IDs?
select i_id from item where i_id not in ( select i_id from review )
How many items did receive reviews?
select count ( distinct i_id ) from review
What are their item ids?
select distinct ( i_id ) from review
What is the rating of item id 3?
select rating from review where i_id = 3